The Cardinals will start three-time All-Star Adam Wainwright, who was pushed back from a scheduled Friday start because of back spasms. Wainwright (5-7, 4.31 ERA) had elbow issues in the 2017 and '18 but is on pace to pitch his most innings since he threw 198 2/3 in 2016.
Wainwright, 37, has thrown 87 2/3 innings this season but he wanted to be cautious after feeling the back spasms Thursday night and letting manager Mike Shildt know.
"I've pitched with way worse back situations than (this)," Wainwright said on MLB.com. "But I told Shildt, 'I want to pitch well.' I feel like I'm on the verge of doing that for a really long time. I don't want to have a setback."
Wainwright is 8-5 with a 2.95 ERA in 15 career appearances (12 starts) against Arizona.
The Diamondbacks will counter with six-time All-Star Zack Greinke, who skipped last week's Midsummer Classic due to personal reasons. He's hoping to pick up where he left off before the break; Greinke (10-3, 2.73) is coming off back-to-back appearances of seven scoreless innings -- at the San Francisco Giants on June 29 and against the Colorado Rockies on July 5.
"Total command of all pitches," is how Rockies manager Bud Black described Greinke's effort on July 5.
Greinke has allowed nine hits, with 15 strikeouts and no walks, in his 14 consecutive scoreless frames.
He has a career mark of 13-5 vs. St. Louis while posting a 3.38 ERA in 20 appearances, including 18 starts.
The Cardinals, who play 17 games in 17 days after the All-Star break, are still looking for more pop from their lineup. Matt Carpenter returned from the injured list (back strain) on Friday, when he hit fifth in the order. He was back in his usual leadoff spot Saturday but went 1-for-5 with four strikeouts. He is hitting .216.
Carpenter does have a .345 average with two home runs in 29 career at-bats vs. Greinke.
Paul Goldschmidt is 0-for-7 in the series, his first against Arizona since an offseason trade from the Diamondbacks.
St. Louis did get a boost Saturday from outfielder Tyler O'Neill, who drove in all four Cardinals runs with a double and a home run after he promised a boy in the Make-A-Wish program before the game that he would hit a home run. O'Neill, who entered with one homer in 66 at-bats this season, did just that in the third inning.
"Seems like a great kid," said O'Neill, who later signed the home run ball for young fan Preston Dobbs. "I was able to put one over the wall for him, so good stuff."
Arizona had won four consecutive games before losing 4-2 Saturday night. Two errors led to three unearned runs.
"It's a little bit frustrating. There were a couple of hiccups and it led to some unearned runs," said Arizona manager Torey Lovullo. "One guy had two really big swings and that's the difference in the game.
"But when you put it all together, there were a bunch of unearned runs, and we don't play that kind of baseball here."
Arizona All-Star Ketel Marte has stayed hot, with two hits Saturday night after hitting his 21st home run of the season Friday night.
--Field Level Media