It’s the first full week of September, and that means plenty of exciting baseball is on tap this week. With less than a month until the end of the regular season, playoff races are taking clearer shape as contending teams begin their postseason push.

• Postseason Watch: Brackets, tiebreakers and more

This week’s action includes a pair of series between American League division rivals -- one in the Central and one in the closely contested West. Two other AL teams fighting to win their divisions will face off in a four-game set this weekend. On the National League side, one of the NL’s top teams travels to face a Wild Card contender, while two other Wild Card hopefuls face each other in what should be a crucial series.

• Complete Major League standings

Here are five series you won’t want to miss this week.

Astros at Rangers
3 games (Monday-Wednesday)

Head-to-head: These AL West rivals will face off for the final time in 2023. In 10 games across their first three series of the season, the Astros are 6-4 against the Rangers, winning three games of a four-game set from June 30-July 3 and taking two of three from July 24-26.

Storyline: In a way, it’s new guard versus old guard in this series. The Rangers haven’t finished a season over .500 or made the playoffs since 2016, but they’re almost certain to accomplish both this season. The Astros, meanwhile, have made four World Series since then, winning it all in 2017 and 2022. The two clubs are in a virtual tie for second place in the AL West, which currently features a historically close three-team race between the Rangers, Astros and Mariners. And if either Lone Star State team hopes to gain ground in September, there’s no better way to do it than in a head-to-head series.

Watch out for: Veteran Astros outfielder Michael Brantley made his long-awaited 2023 debut on Tuesday in Boston after recovering from an August 2022 shoulder surgery. On Wednesday, his second game after a 14-month absence, Brantley went 2-for-4 with a double and two RBIs. He homered on Saturday in his first 2023 start at Minute Maid Park. Brantley is a key piece of the Astros’ lineup, and his return will add to Houston’s depth for this series and down the stretch.

Giants at Cubs
3 games (Monday-Wednesday)

Head-to-head: This pair of NL teams met back in June for a three-game series at Oracle Park, with the Cubs taking the first two games on the road.

Storyline: What better series to highlight than a September set between two of the National League’s top Wild Card contenders? The Cubs hold the second Wild Card spot, with the Giants in a three-way tie with the Marlins and D-backs for the third and final position (and the Reds in a virtual tie as well). These two clubs match up well, with NL Cy Young Award contenders Logan Webb and Justin Steele set to face off on the mound on Monday. The Giants took two of three from the Reds before dropping three of four games in San Diego, while the Cubs have been hot for months -- their .646 win percentage since the All-Star break ranks fourth in MLB.

Watch out for: Cubs outfielder Ian Happ has hit in 17 of 19 games since Aug. 15. Happ has hit .385 and slugged .769 since Aug. 28, pacing a Cubs offense that ranks fifth in batting average (.266) and seventh in OPS (.795) since the All-Star break. Happ and the resurgent Cody Bellinger form a formidable duo in the middle of Chicago’s solid lineup.

Twins at Guardians
3 games (Monday-Wednesday)

Head-to-head: These two teams just met in Minneapolis, with the Guardians taking the second and third games to claim the series win. Cleveland owns a 6-4 record against Minnesota in 2023.

Storyline: This series is the final head-to-head opportunity for the Guardians to make up serious ground in the AL Central race. At 66-71, Cleveland is five games back of Minnesota -- within striking distance with a month left in the season. While the Guardians’ sub-.500 record means an AL Wild Card berth is highly unlikely, their 6-4 mark against the team they’re chasing is a reason for optimism. The Twins could play themselves into the AL’s No. 2 seed (and thus a first-round bye) with a scorching September, but it would take nearly flawless baseball this month -- and they can’t afford to trip up in this series against a division rival.

Watch out for: Twins starter Sonny Gray is coming off back-to-back seven-inning starts, including a shutout outing on Wednesday against the same Guardians he’ll face on Tuesday. Gray allowed just one run in his other appearance -- against the Rangers on Aug. 25 -- and his ERA is now down to 2.92 -- third-best among qualified MLB starters.

Dodgers at Marlins
3 games (Tuesday-Thursday)

Head-to-head: Just a couple weeks ago at Dodger Stadium, these two teams played their only other series of 2023. The Marlins dominated Game 1 before the Dodgers swept a doubleheader on Aug. 19 to take two of three.

Storyline: The Dodgers have basically already salted away the NL West, but they’re still in the mix for the NL’s No. 1 seed. L.A. is already likely to earn a top-two seed and thus a bye into the NL Division Series, although losing three of four games over the weekend to the top-seeded Braves didn’t help. There’s probably more at stake for the Marlins, who were in a three-way tie for the third NL Wild Card spot after a four-game sweep of the Nationals. Their 17-28 record since the All-Star break is tied for fourth-worst in MLB, but the Marlins still have a good shot at the postseason -- and taking down the Dodgers at home would go a long way.

Watch out for: Marlins third baseman Jake Burger clubbed a pair of home runs Saturday against the Nationals to reach 30 homers on the season. After being dealt from the White Sox at the Trade Deadline, Burger has excelled for his new team, hitting .313/.366/.509 with the Marlins. The former first-round Draft pick has been a key piece of a Miami lineup that also added Josh Bell at the Deadline.

Mariners at Rays
4 games (Thursday-Sunday)

Head-to-head: The Mariners and Rays met for three games from June 30-July 2 in Seattle, with the home team taking the final two games after a Rays rout in the opener.

Storyline: This four-game series is critical for both teams. For one, the head-to-head tiebreaker is still very much up for grabs; that could determine who gets a higher seed, who gets home-field advantage or even who gets a playoff spot and who will be left out. Both teams, of course, harbor hopes of winning their respective divisions. The Mariners have a one-game lead on the Astros and Rangers in the AL West; the Rays are just 2 1/2 games behind the Orioles in the AL East. Even if neither team wins its division, this four-game set has significant Wild Card implications.

Watch out for: Who else but Julio Rodríguez? The American League Player of the Month had a scorching August, hitting .429/.474/.724 and breaking a record for hits in a four-game span. Rodríguez has helped power the Mariners to a 32-15 record since the All-Star break -- the second-best mark in MLB -- and he hasn’t shown any signs of cooling down just yet.