St. Louis Cardinals' Matt Carpenter watches his grand slam against the Chicago Cubs during the first inning in the first baseball game of a doubleheader, Wednesday in Chicago. (AP Photo/David Banks)

CHICAGO (AP) — Matt Carpenter belted a grand slam and the St. Louis Cardinals beat the Cubs 9-3 in Game 1 of a doubleheader on Wednesday, holding Chicago to two hits even though a shaky Jack Flaherty couldn’t make it out of the second inning.

Flaherty gave up a leadoff homer to Ian Happ and recorded just five outs in his first start since a season-opening win over Pittsburgh.

“The offense was really fun to watch today,” Flaherty said. “Going out there in the first and putting up a four spot and kind of giving me a little bit of room to breathe and go out and work on executing pitches. They didn’t stop there, though. When you get four in the first it’s real easy to kind of call it a day, but they kept going at it.”

Carpenter drove a rope to center in the first against Alec Mills (2-2) for his second career grand slam. Tommy Edman had three hits and Kolten Wong scored four runs.

Tyler Webb (1-1) got four outs and the Cardinals got back to winning after dropping two straight to the NL Central leaders. Baseball’s seven-inning doubleheader format, implemented this season to help teams push through a frequently disrupted 60-game schedule, allowed St. Louis to use four relievers for 1 1/3 innings apiece after Flaherty’s exit.

Happ hit the right field video board with his team-leading sixth homer — and third in four games. The Cubs’ only other hit was a Josh Phegley two-run homer in the seventh.

In Game 2, David Bote hit a tiebreaking two-run single in the seventh and final inning, Adbert Alzolay pitched five solid innings in his first start of the season, and the Chicago Cubs beat the St. Louis Cardinals 4-2 on Wednesday night to split a doubleheader.

St. Louis’ Brad Miller hit a tying RBI single in the bottom of the sixth against Jeremy Jeffress (2-1).

Playing as the visitor in the nightcap because the game was a makeup from a postponed series in St. Louis from earlier this month, the Cubs loaded the bases against Andrew Miller (0-1) on singles by Kyle Schwarber, Willson Contreras and Nico Hoerner with one out. Bote, then lined a single to center against Giovanny Gallegos, making it 4-2 and propelling the Cubs to their third win in four games.