Wainwright looks to build on one of his best starts and lead the Cardinals to their sixth win in seven games Friday night against the visiting NL East leaders.
Matt Holliday continued his tear at Busch Stadium with two doubles as St. Louis won for only the second time in 10 regular-season meetings with a 6-2 victory in Thursday's series opener. He is batting .458 with four homers and 14 RBIs during a 14-game home hitting streak.
The Cardinals (74-53) remained one game behind Pittsburgh for the NL Central lead.
The Braves (77-50), meanwhile, have a comfortable 14-game bulge atop the East, but have totaled 11 runs and hit .237 while splitting their last four contests.
They might have a difficult time regrouping against Wainwright (14-7, 2.66 ERA), who ranks among the top 10 in the majors in ERA and strikeouts. After going 0-2 with a 4.18 ERA over his previous four starts, the All-Star right-hander fanned 11 while allowing one run and five hits over seven innings in beating the Chicago Cubs 6-1 on Sunday.
"It's as good as he's been all season,'' manager Mike Matheny said. "He came out in the first and established all his pitches, had great life. His curveball was as sharp as we've seen it.''
Wainwright, however, has had some trouble with the Braves lately. Since winning his first six starts against them, he's allowed nine runs and 16 hits over 11 1-3 innings while dropping his last two. He struck out eight and gave up four runs over seven innings in a 4-1 loss at Atlanta on July 26.
Jason Heyward homered off Wainwright in that meeting, but he's sidelined at least four weeks after suffering a broken jaw after being hit by a pitch Wednesday.
Teammate Justin Upton belted his 24th home run Thursday after missing three games with a strained upper back. He's hitting .375 with eight homers and 17 RBIs in his last 18 games.
Chris Johnson (.330) is 4 for 11 in this matchup the past two seasons, but went 0 for 3 Thursday to fall behind St. Louis catcher Yadier Molina (.332) in the NL batting race.
Molina is expected to return to the lineup after Matheny rested him Thursday. He's 3 for 7 lifetime against Kris Medlen (10-11, 3.71), who will try to win his fifth straight start.
The right-hander made his first relief appearance Saturday, giving up a go-ahead home run to Adam LaRoche in the 15th inning of an 8-7 loss to Washington. He allowed one run and four hits over his three innings.
"It's a situation I've been in before," Medlen said. "Once you've experienced it before you want to get into the game and be part of it.''
Medlen's winning streak as a starter began July 28, when he limited the Cardinals to two runs in six innings of a 5-2 victory.
This time, he faces a St. Louis team that has averaged 6.2 runs and batted .294 over its last five games.
Carlos Beltran is 9 for 18 with two home runs over his last four games, while Matt Carpenter - who has posted 30 of his NL-leading 49 multihit games at home - is 15 for 29 with six doubles over his last six there.