He'll try to replicate that effort in order to snap his personal losing streak, as the Cardinals go for another victory over their NL Central rival on Wednesday night.
Wacha (2-3, 2.85 ERA), the 2013 NL championship series MVP, is seeking his first win since April 13, when he allowed three runs with eight strikeouts in 6 1-3 innings of a 6-4 victory over the Cubs.
The right-hander is 0-3 with a 3.49 ERA in five starts since - all losses for St. Louis (20-20). He hasn't received much help from his offense as the Cardinals have backed him with eight total runs of support in those games.
Wacha received no help at Chicago on May 3, when he gave up two runs with six strikeouts in six innings of a 3-0 defeat.
He followed that up six days later by surrendering three runs in five innings while not getting a decision in a 6-4 loss at Pittsburgh. Five of the seven hits he gave up came with two strikes, and he holds opponents to .133 in that scenario through his first two seasons.
He is also fifth in the NL with 57 strikeouts.
"You get hitters to two strikes and you want them to have a little tougher time than that," manager Mike Matheny told the team's official website. "Typically, he's the guy who can get the swing and miss. It comes a little easier sometimes than others."
The Cardinals didn't even need to swing the bat to beat the Cubs 4-3 on Tuesday, drawing back-to-back walks to load the bases in the 12th before pinch-hitter Greg Garcia was hit by a pitch with two strikes.
"I saw the pitch out of his hand and knew it was in," Garcia said. "When it got close to the plate I saw it had a chance to hit me. I'll take that one 100 percent of the time."
The Cubs (13-25) have dropped eight of 10, but have totaled 30 hits through the first two of this four-game set. They pounded out 20 hits in Monday's 17-5 win, as Emilio Bonifacio scored five times and had four hits before adding a pair of singles and an RBI on Tuesday.
Jason Hammel (4-1, 2.45) is expected to take the ball, and he ranks fourth in the majors with a 0.86 WHIP.
The right-hander is 2-0 with a 2.00 ERA over his last four starts. He's pitched well enough to win his last two, allowing five runs in 13 innings, but hasn't been involved in the decisions while being backed by three total runs.
"Wins and losses are unfair," Hammel told the team's official website. "You have no control over wins and losses. Say you pitch well and lose, 1-0. You deserved a win. Sometimes you give up eight runs and your team scores nine, and you should probably lose that game.
"I honestly think WHIP, out of all the pitcher-type things, WHIP is the most important one. If you're constantly having runners on base, you're not doing your job."
Hammel owns a 1.63 WHIP while going 1-1 with a 5.28 ERA in three career starts against the Cardinals. He gave up three runs and seven hits in six innings while not getting a decision in a 5-4 loss to them May 4.