What would have been one of the Astros’ most satisfying wins of the season turned into one of their most devastating losses on Saturday, and not just because of the result on the field.

After rallying for three runs in the top of the ninth inning, capped by a dramatic two-out, two-run homer by George Springer to take the lead, the Astros lost closer Roberto Osuna to an arm injury in the bottom half and then let the game slip away in the 10th in a 5-4 loss to the Angels at Angel Stadium.

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“My dad told me, 'Don’t think worse because it can get worse,'” said Astros manager Dusty Baker, whose pitching staff has been ravaged by injuries in the first week of the season. “That was a terrible, terrible, terrible blow.”

The Angels rallied to tie the game on an RBI double by Jason Castro off Cy Sneed, who replaced the injured Osuna, and won it in the 10th on a walk-off sacrifice fly by Michael Hermosillo against rookie Nivaldo Rodriguez. The Astros are 0-2 in extra innings this year.

Baker said Osuna was scheduled to fly back to Houston to undergo an MRI to determine the extent of the injury, which happened when he threw a pitch to Castro in the ninth. Osuna immediately signaled for head athletic trainer Jeremiah Randall and Baker to come to the mound.

“It’s a real downer when he signals you to come out,” Baker said. “I feel like, ‘Boy, this is not the news you want to hear.’ We just have to wait and see after he sees the doctors.”

Coming into Saturday’s game, the Astros already had 10 rookie pitchers in their bullpen because of injuries and the expanded rosters as a result of the coronavirus. Seven pitchers have made their big league debuts this year for Houston.

The injury to Osuna means the only healthy pitcher in the bullpen not a rookie is All-Star setup man Ryan Pressly, who made his 2020 debut Saturday in the eighth inning. He had been dealing with elbow soreness the first week of the season. Randall and Baker had to go to the mound to check on Pressly, who wound up having a cut on the cuticle above his thumbnail.

“Fortunately for us, he was alright,” Baker said. “We got him out of there because we didn’t want him to throw too many pitches because that’s his first outing.”

Baker said left-hander Framber Valdez, who started Tuesday’s game against the Dodgers, will likely be available to throw in relief on Sunday. The rotation is already without Justin Verlander, who strained his forearm in his first start and will be shut down for another week.

When the Astros placed veteran reliever Chris Devenski on the injured list on Saturday, they activated Carlos Sanabria, who was on the traveling taxi squad and pitched at Double-A last year. Another taxi squad pitcher, Humberto Castellanos, could become the club’s 11th rookie on the big league roster if he’s activated on Sunday to replace Osuna.

Baker didn’t hide his concern of the dire pitching situation. In addition to Verlander and Devenski, veterans Brad Peacock, Joe Biagini and Austin Pruitt are on the IL, and the club has been without veteran Joe Smith, who’s on the restricted list.

“When the sun goes down, sometimes there’s sadness and the sun comes back up and the heart can find some joy in some place the next day,” Baker said. “So it’s not easy to go to sleep tonight, but the sun will come up tomorrow.”

Things seemed much better when the Astros, trailing 3-1 entering the ninth, rallied behind a solo homer by Josh Reddick and a two-out, two-run homer by Springer to put Houston ahead. Osuna retired Albert Pujols to start the bottom of the ninth and gave up an infield hit to Luis Rengifo before calling for a trainer after throwing a pitch to Castro.

“This is a league-wide thing,” Springer said about the rash of injuries. “You’re seeing a lot of guys throughout the league starting to get injured, a lot of pitchers. It’s scary, especially when it hits home. Osuna has been, obviously, an absolute anchor for us. For anybody who goes down, it’s hard for us.”