ST. LOUIS -- After a blowout win in Game 1 on Thursday, the Cardinals looked poised to sweep the twin bill against the Tigers with solid pitching and the offense backing it up.

It fell apart in the final inning of the seven-inning doubleheader.

The Tigers scored five runs to snatch the lead and hand the Cardinals a 6-3 loss, splitting the doubleheader in the two-game, one-day series at Busch Stadium. It also put their bullpen in a precarious spot.

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After closer Giovanny Gallegos put two runners on with no outs, he exited the game with a groin injury. Manager Mike Shildt says he thinks it’s the right groin; the Cardinals will know more after Gallegos undergoes imaging Friday to determine the severity. It’s likely he could miss some time, which will reshuffle roles in the bullpen again.

“It was pretty clear he wasn’t able to continue,” Shildt said. “He’s getting it looked at. Clearly couldn’t continue to compete.”

For Gallegos’ last batter faced, a throw from center fielder Harrison Bader put the Cardinals in a compromised position. Jonathan Schoop hit a single into center field, and Bader misguided it home so that it landed up the line -- and actually hit Miguel Cabrera in the on-deck circle. That allowed the runners to advance to second and third, changing the Cardinals' plan.

With a base now open and St. Louis leading, 3-2, Ryan Helsley intentionally walked Cabrera. But that brought Jeimer Candelario -- who was 5-for-6 with a walk and two home runs across both games Thursday -- to the plate. The Cardinals were now playing for a tie and hoping to get a double-play ball from Candelario.

Candelario delivered a two-strike, two-run single to center field.

“Pick your poison,” Shildt said. “You’re talking about a Hall of Famer. The guy’s driven in a lot of runs for a lot of years. You don’t have a force with him, you’re playing for the punchout, trying to pitch careful -- it’s not a great recipe for an experienced hitter. So you go ahead and set up a force [out]. Give Candelario credit, he got a ball that was up a little bit with two strikes.

“Took one of their better hitters off the board, still have a chance at that point. But it wasn’t meant to be that second game.”

And after a double play put the end in sight, Jorge Bonifacio launched a 402-foot home run into the Tigers' bullpen to put the comeback out of reach for the Cardinals in the bottom of the inning.

“I haven’t gotten a chance to go look at it yet, but I think it was a bad pitch,” Helsley said. “You just try to go out there and give it your best. Try to make sure you’re loose -- you get as much time as you need. I thought I was ready to go and get the job done.”

As packed as the Cardinals' schedule is with games, the importance of winning is greater now, especially as the race to the postseason has now become a sprint. St. Louis lost a chance to sweep a doubleheader against the sub-.500 Tigers heading into a gauntlet of games against the Reds (three games this weekend) and Brewers (five games in three days next week).

The way it happened made it all the more heartbreaking. Austin Gomber delivered three scoreless innings in his second spot start and Alex Reyes got out of a no-outs, bases-loaded situation without no damage in the fourth inning. Matt Carpenter (two RBIs) and Tommy Edman (solo home run) delivered the offense and the lead.

“It’s a bummer,” Edman said. “We thought we had that game in the bag with how good our bullpen’s doing. No pitcher is going to be perfect every time out. They’ve been dominant all year, so that’s what our expectation has been.”

The high-leverage relievers worked around trouble until they couldn’t anymore. Bader’s throw opened a base, and Candelario turned it into a loss. Gallegos' status remains unknown and could force rearranging in the bullpen heading into a difficult stretch of games.

“Yeah, that one stung,” Shildt said. “But we’ll move on and get ready tomorrow.”