HOUSTON -- Astros right-hander Lance McCullers Jr. was dropped from the team’s roster for the American League Championship Series on Friday after he was diagnosed with a right flexor pronator muscle strain, an injury suffered in his start in Game 4 of the AL Division Series on Tuesday in Chicago.

That means McCullers won’t be available for the Astros in the ALCS, punching a huge hole in Houston’s starting rotation before a best-of-seven series against the Red Sox. Astros general manager James Click said an MRI performed on McCullers' arm revealed no structural damage.

McCullers’ availability for the World Series, if the Astros advance, depends on how much recovery time it takes and how quickly the muscle responds to treatment.

“Hopefully, that’s a question that we have to answer in eight or nine days,” Click said.

Astros shortstop Carlos Correa, who’s a close friend of McCullers, said the righty texted him and said, ‘Sorry, I couldn’t keep going for you guys.’ Correa said it was a “very emotional” time.

“Not having him is a tough situation,” Correa said. “At the same time, we have a lot of guys that are here and capable of getting the job done, and we believe and we trust in them. We have to go out there and take care of business, and at the end of day we’ve got to hit, and we’re looking forward to having a great series against the Red Sox.”

Astros pitcher Jake Odorizzi suffered a right pronator muscle strain in April and missed a month of the season. Odorizzi and left-handed reliever Blake Taylor were added to the ALCS roster, with McCullers and catcher Garrett Stubbs getting dropped. Houston is carrying 13 pitchers for the best-of-seven series against the Red Sox.

Astros manager Dusty Baker said Odorizzi could start in Game 4. He went 1-1 with a 2.93 ERA in his final seven starts to end the season before being left off the ALDS roster. He hasn’t pitched since Oct. 2.

“He was disappointed because he wasn't on the [ALDS] roster, but I said, ‘Hey, you know, we got the next series,’” Baker said. “Didn't have any idea that this would happen, but that's how it's been for us all year. We had one guy, he was injured, and then next thing you know we get a guy back and then we lose a guy and then get another guy back and lose a guy, and we just got to keep on trucking.”

McCullers, who signed a five-year, $85 million contract extension in the spring that’s set to begin next year, had the best season of his career, going 13-5 with a 3.16 ERA that was second in the AL. The Astros won both games in the AL Division Series started by McCullers, who held the White Sox to one run on nine hits in 10 2/3 innings.

McCullers pitched in relief through a torn ulnar collateral ligament in his right elbow during the 2018 ALCS against the Red Sox and eventually had Tommy John surgery. He missed the entire '19 season.

Martín Maldonado, starting catcher: Maldonado had a bad year on offense in the No. 9-hole, but a combination of veteran leadership, defense and his throwing arm keeps him in the lineup. He caught the second-most innings in the Major Leagues this year (1,010 2/3) in the regular season and ranks fourth in caught stealing percentage (39.6). Offensively, his .573 OPS and 58 OPS+ are among the worst in MLB. But the Astros were 72-46 when Maldonado started, 19-18 when Jason Castro started and 4-3 when Garrett Stubbs started.

Jason Castro, backup catcher: Castro, who didn’t play in the ALDS, re-signed this year with the club he broke into the Major Leagues with to serve as Maldonado’s backup. He may start once in a series, if at all. This season, he started 37 games as the backstop, and he generally brings a bit more offense than Maldonado. Castro draws walks, has some pop (eight homers in 149 at-bats) and had a .799 OPS. There’s a falloff defensively, though, because Castro has thrown out only 12.9 percent of attempted steals (4-of-31).

Yuli Gurriel, starting first baseman: One of the best defensive first basemen in the game, Gurriel, 37, has enjoyed a bounceback year at the plate, and he became the second Astros player to win a batting title by leading the AL with a .319 average. Defensively, he has blossomed into one of the steadiest hands at first base, and he has saved numerous errors by his infielders by scooping out low throws with ease.

Jose Altuve, starting second baseman: Altuve, who was named to his seventh All-Star team this year, isn’t the offensive player he once was, but he tied a career high in homers (31) this season while taking over for George Springer in the leadoff spot. He’s one of the most experienced postseason players in the game and is tied for fourth all-time with 19 playoff homers, including his pennant-clinching walk-off against the Yankees in 2019. Altuve has also displayed no troubles throwing the ball to first base, which was an issue for him a year ago.

Carlos Correa, starting shortstop: If the name “Mr. October” weren't already taken, it could apply to Correa, who’s one of the most clutch playoff performers in history. He’s tied for 10th all time with 17 career postseason homers across five seasons. Correa, a free agent at the end of the year, had one of his best years offensively in 2021, hitting a career-high 26 homers while managing to remain healthy and in the lineup. He also continues to play at an elite level at shortstop and is unquestionably the Astros’ leader on and off the field. And he’s only 27 years old.

Alex Bregman, starting third baseman: Bregman missed 59 games in the middle of the season while overcoming a strained left quad, but he has been a productive and dangerous player when healthy. He has hit 11 career postseason homers -- all off All-Star pitchers, including Chris Sale, Clayton Kershaw, Kenley Jansen, Corey Kluber, Trevor Bauer, Blake Snell, Chris Bassitt and Stephen Strasburg (two in the 2019 World Series). Bregman revels in big moments and big situations and always plays with a chip on his shoulder.

Michael Brantley, starting left fielder: Any concerns about Brantley’s balky right knee went out the window in the ALDS, where Brantley started three of four games in left field and once at DH. Brantley remains an elite hitter -- he tied with Toronto’s Vladimir Guerrero Jr. for second in the AL in batting average this year at .311 -- but he doesn’t hit for much power anymore. Still, he’s a bat the Astros sorely need in the order.

Jake Meyers, starting center fielder: Meyers stayed on the roster for the ALCS after banging his left shoulder into the wall trying to catch a ball in Game 4 of the ALDS. Called up at the Trade Deadline after the Astros dealt Myles Straw to Cleveland, Meyers was slated to be the club’s fourth outfielder, with Chas McCormick taking over as the starter in center. When Kyle Tucker went on the COVID-19 IL, McCormick started in right.

Kyle Tucker, starting right fielder: Tucker emerged as a force in the middle of the Astros’ lineup and has had a career year, shaking off a slow start (he hit .188 with a .651 OPS in his first 34 games of the season). Tucker finished third in the AL in OPS (.917) behind Guerrero and the Angels' Shohei Ohtani, hit a career-high 30 homers and was named the AL Player of the Month for September/October. He has been a surprisingly solid fielder, too, leading AL right fielders in fielding percentage (.992) and zone rating (.948).

Yordan Alvarez, designated hitter: After being limited to two games in last year's abbreviated season following surgery on both knees in August, Alvarez had the kind of year the Astros had hoped following his incredible 2019 AL Rookie of the Year Award campaign. He led the team in homers (33) and RBIs (104) and proved to be a proficient left fielder, where he played quite a bit after being limited to DH duties to start his career. Alvarez hits cleanup in one of the most dangerous lineups in baseball.

Aledmys Díaz, utility infielder: Díaz will be the Astros’ first position player off the bench and first pinch-hit option, though he got one at-bat in the ALDS. He can play left field and all four infield positions, so he will be a valuable asset for manager Dusty Baker and his coaching staff in the postseason. Expect Díaz to pinch-hit if the Astros decide to hit for Maldonado at some point. Díaz missed 43 games because of a broken left hand suffered in June, but he slashed .337/.368/.525 with four homers and 19 RBIs in his first 24 games after returning in late July.

Jose Siri, backup outfielder: Siri is an enigma. He has tremendous power and can run fast, but he plays out of control at times and has a lot of swings and misses. He’s the kind of player who could make an incredible play, only to make a bigger mistake later. The Astros have been getting inconsistent production from center fielders McCormick and Meyers down the stretch, which may have opened a spot for Siri, but he’s probably limited to pinch-running at this point.

Chas McCormick, backup outfielder: McCormick and Meyers figure to split time in center at this point. Both play strong defense and have a lot of swing-and-miss in their game, but Meyers slumped down the stretch after a strong August. McCormick doesn’t get cheated on swings and has raw power. If he’s not starting, he’s likely one of the first players off the bench. He could serve as a pinch-runner or defensive replacement for Brantley in left field late in games.

Framber Valdez, starting pitcher: Valdez, a lefty, was better against right-handers (.626 opposing OPS) in the regular season than against left-handers (.717), thanks to one of the best curveballs in the league. That’s crucial against the Red Sox and their right-handed-heavy lineup. Valdez’s key will be controlling his walks. He averaged 3.88 walks per nine innings. Sidelined for the first two months of the season because of a broken left ring finger suffered in Spring Training, he went 11-6 with a 3.14 ERA in 134 2/3 innings, allowing 110 hits (12 homers) and 58 walks with 125 strikeouts.

José Urquidy, starting pitcher: Urquidy, who burst onto the scene in Game 4 of the 2019 World Series with five scoreless innings on the road against the Nationals, will likely start the third game of the ALCS after not pitching in the ALDS. He pitched around a pair of right shoulder injuries -- one of which kept him out in July and August -- and posted a 3.62 ERA and a 0.99 WHIP in 107 innings. Urquidy is a strike-thrower who could be a candidate to be piggybacked by Zack Greinke, because he hasn’t thrown more than 91 pitches in a start since June.

Luis Garcia, starting pitcher: Garcia, who’ll likely get some AL Rookie of the Year Award votes, will start Game 2 in Houston, where he’s much better than he is on the road. Garcia blew past his previous career high by throwing 155 1/3 innings, striking out 167, and he pitched more than five innings only five times in his final 12 starts. Garcia averaged only 82.4 pitches in his final five starts of the year as the Astros pulled back on his innings load.

Zack Greinke, long relief: Greinke was in the bullpen for the ALDS and pitched only one inning. He could be a candidate to make a start in Game 4 of the ALCS with McCullers out. Greinke missed time in September with a positive COVID-19 test and another IL stint with neck soreness, which hampered his ability to build up his strength before the end of the season. He made his first relief appearance since 2007 in the regular-season finale on Oct. 3 and allowed two runs in 2 1/3 innings.

Jake Odorizzi, long relief: Odorizzi’s spot on the postseason roster was a tenuous one, which led to him being left off the ALDS. He could be a candidate to start Game 4 or pitch in long relief in the ALDS. Odorizzi didn’t sign with the Astros until March, and he made three starts (10.13 ERA) to begin the season before going on the IL on April 26 for a month with a right pronator strain. He appeared in 21 games (20 starts) since coming back and went 6-5 with a 3.72 ERA, missing a few starts in September with a sore right foot. He didn’t pitch more than five innings in his final six starts, which was a point of contention for him at one point.

Ryan Pressly, closer: One of the best closers in baseball, Pressly didn’t put up gaudy save numbers because the Astros blew so many teams out and weren’t great in close games. Pressly hasn’t pitched more than one inning a game since early in the season, as the Astros prefer him to be a one-frame closer. He averaged 11.4 strikeouts per nine innings and posted a 0.97 WHIP while converting 26 of 28 saves.

Kendall Graveman, setup: Graveman was acquired in a July trade with the Mariners to be the Astros’ eighth-inning setup man, helping them bridge the gap to Pressly more efficiently. Graveman posted a 0.82 ERA and 0.70 WHIP in 33 innings with Seattle but a 3.13 ERA and 1.39 WHIP in 23 frames with Houston, with his walk numbers going up. Right-handers couldn’t touch him this year (.348 OPS), but left-handers had more success against him (.748 OPS). He figures to be a good matchup against the Red Sox, given their right-handed-heavy lineup.

Ryne Stanek, setup: Stanek was the Astros’ primary eighth-inning setup man before they acquired Graveman, pushing Stanek to the seventh inning in Baker’s ideal bullpen alignment with a lead. Like Graveman, lefties have hit him much harder (.817 OPS) than right-handers (.482), meaning he would be a weapon in the ALDS. Stanek can get himself in trouble with walks.

Yimi García, reliever: García, who came over in a July trade from the Marlins, gave up a key homer in Game 3 of the ALDS but got some huge outs in Game 4. In the regular season, he had a 5.48 ERA with the Astros, and he allowed three homers in 21 1/3 innings. You can expect Baker to use him in key situations against righties, who posted a .587 OPS against him this year. Lefties (.843) hit him much better, so the Astros would be wise to keep southpaw bats away from him.

Phil Maton, reliever: Another midseason trade acquisition, Maton struggled in the regular season, posting a 4.97 ERA and 1.58 WHIP with the Astros, but he appeared in three games in the ALDS and pitched three scoreless innings. Right-handers (.797 OPS) have hit him better than lefties (.726) in the regular season, and he’s emerged as a right-handed pitcher who’s a weapon against left-handed hitters in much the same fashion that Will Harris was for the Astros in 2019.

Cristian Javier, reliever: The Astros moved Javier to the bullpen early in the season because they had a wealth of starting pitching, but they struggled to find a consistent role for him. His command suffered as a result. Javier, who averaged 11.5 strikeouts per nine innings, walked 21 batters in 48 2/3 innings as a starter and 32 in 52 2/3 innings out of the bullpen. He figures to be called upon to get some key outs in the ALCS.

Brooks Raley, lefty specialist: Raley was third on the Astros in appearances (58) behind the back-end combo of Stanek and Pressly. Raley has swing-and-miss stuff and thrives off soft contact, though he has a penchant for allowing homers (six in 49 innings). He has a 31.7 strikeout percentage and a 7.8 walk percentage, which is excellent. Raley struck out 35 of the 85 lefties he faced in the regular season -- without much in terms of a high-velocity approach.

Blake Taylor, lefty specialist: Taylor wasn’t on the ALDS roster against a right-handed-heavy White Sox lineup in the ALDS, but he’ll join Brooks Raley as the two lefties in the bullpen against the Red Sox in the ALCS. Taylor can get some swings and misses on his slider and he pitched better in the second half (2.35 ERA) than he did in the first half (4.12 ERA).