Michael McLoone-USA TODAY Sports

St. Louis Cardinals pitcher Jack Flaherty's search for his pre-injury form will continue Sunday against the visiting Chicago Cubs.

Flaherty (0-0. 7.50 ERA) will make his third start since coming off the 60-day injured list when the Cardinals and Cubs play the rubber game of their three-game series.

The Cubs won 3-0 Friday, and the Cardinals bounced back to win 5-3 on Saturday.

After missing the first 2 1/2 months of the season with shoulder bursitis, Flaherty, a right-hander, has struggled to find and repeat his mechanics. He lasted just three innings in each of his two starts, including walking five Brewers in the Cardinals' 6-2 win on Tuesday.

"Game didn't go that well," Flaherty said. "I didn't really have good stuff. I didn't have good command or anything. But to keep the game right there give us a fighting chance."

In retrospect, perhaps Flaherty needed a few more rehabilitation starts in the minors before returning to the majors.

"You're weighing it against the other options in that spot of the rotation," Cardinals manager Oliver Marmol said. "So you're weighing the option of could it be better with Jack building here? And our vote was yes. His vote was yes. Has it looked the way we wanted it to? No. Are we confident as a competitor he'll figure it out his next outing? Yes."

The Cardinals' bullpen behind Flaherty will be compromised Sunday. Genesis Cabrera landed on the 10-day injury list Saturday, prompting Jake Woodford's arrival from Triple-A Memphis.

Late-inning relievers Giovanny Gallegos threw 32 pitches and Ryan Helsley threw 36 Saturday as they covered the last three innings for the Cardinals. Their availability for Sunday is questionable.

Right-hander Alec Mills (0-1, 8.59 ERA) will come out of the bullpen make his first start of the season for the injury-depleted Cubs. He worked 4 1/3 innings Monday in relief in his last outing, a 12-1 loss to the Pittsburgh Pirates, while allowing five runs on eight hits. He also hit a batter.

Mills has not faced the Cardinals this season. He is 0-2 with a 4.26 ERA in seven career appearances against them, including five starts.

Cubs outfielder Ian Happ recorded his 46th career RBI against the Cardinals on Friday. He is 1-for-4 against Flaherty, with a home run and two walks in his career.

"He's held down the middle of our order when we've lacked some of that consistency in the middle," Cubs manager David Ross said. "He's definitely been one of our All-Stars for sure."

Happ is 29-for-83 in June with eight doubles, three homers and 10 RBIs. He is 9-for-26 with a homer and four RBIs against the Cardinals this season.

"Being able to play left field here every day and hit in the middle of the order is something that has been awesome," Happ told NBC Sports Chicago. "My focus is continuing to do that for as long as I possibly can."

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