NEW YORK -- Six seasons as the manager of the St. Louis Cardinals has taught Mike Matheny there are plenty of times he has to make a decision with which Matheny the big league player might not have agreed.

But Matheny the manager and Matheny the former catcher both wanted -- and got -- the same thing Tuesday night, when Michael Wacha threw the first career complete game of his professional career, a three-hit shutout, as the Cardinals cruised past the New York Mets 5-0 at Citi Field.

"Both sides of me wanted to see him get that," said Matheny, who played 13 seasons in the majors and was the Cardinals' catcher from 2000 through 2004. "I don't want to take away a special opportunity like that. When you pitch that well, you should get a chance to finish what you started."

It was up to Matheny in the first half of the season to ensure Wacha -- who was sidelined by shoulder issues in 2014 and 2016 -- would never get the chance to even ponder a complete game. Wacha threw more than six innings just once in 16 starts prior to the All-Star break and took the mound Tuesday on 11 days' rest.

But it didn't take long for Wacha to show he was ready to swim into uncharted territory. The 26-year-old right-hander, who walked one and struck out eight, mixed his changeup with a mid-to-high 90s fastball in authoring three streaks in which he retired at least seven straight batters.

Wacha (7-3) threw 15 pitches or fewer in six innings, including four straight from the fifth through the eighth.

"He was so efficient through the seventh and the eighth that he wasn't even working that hard," Matheny said.

Wacha, who threw eight innings just twice in his first 107 career starts, told Matheny after the eighth that he felt fine. Wacha's bid became endangered in the ninth, when he allowed a leadoff single to Michael Conforto and threw a wild pitch.

But Wacha retired the final three batters he faced and capped the gem by striking out Jay Bruce with his 24th pitch of the inning and the career-high 119th of the game.

Wacha, who has won four straight starts, pumped his fist before exchanging hugs with catcher Yadier Molina following just the 18th individual shutout in the majors this season.

"Just kind of relief -- hot night out there," Wacha said of his emotions following the final out. "But it was just a lot of fun. First one, it's very cool."

The complete game by Wacha -- his first since he was a junior at Texas A&M in 2012 -- spared a Cardinals bullpen that gave up seven runs over 11 2/3 innings in the first four games following the All-Star break.

"Just a great day for him. We hate pushing him that hard, but we needed that," Matheny said.

Wacha has a 1.01 ERA in his last four starts, a stretch in which he has struck out 31 and walked just five over 26 2/3 innings.

Matt Carpenter had four hits for the Cardinals (46-47), who have won the first two games of the four-game series. Carpenter led off the game with a double, went to third on an error by Mets third baseman T.J. Rivera and scored on a sacrifice fly by Jedd Gyorko.

The Cardinals scored three runs in the second, when Wacha was credited with an RBI after beating out the back end of a potential double play. Carpenter followed with an RBI double and Wacha eventually scored on an error by T.J. Rivera.

Molina had an RBI single in the seventh inning.

Conforto had two hits, including a double in the sixth, while Yoenis Cespedes singled in the first for the Mets (41-50), who committed three errors in losing their three straight.

"Wacha pitching like he did tonight -- a pretty dominant performance -- you let him have some extra runs, they're going to beat you," Mets manager Terry Collins said.

Mets right-hander Rafael Montero (1-6) allowed four runs (two earned), seven hits and one walk while striking out five over six innings. Montero allowed just one runner to get beyond first base in his final four frames.

"After the second inning, things could have broke down on him," Collins said. "First couple of innings, we make a couple of plays, it's a different situation."

NOTES: Mets LHP Josh Smoker (left shoulder) moved his rehab to Double-A Binghamton on Tuesday night, when he allowed two hits in a scoreless inning. ... Cardinals INF Matt Carpenter has reached base safely in 21 straight games, which ties C Yadier Molina for the longest streak by a Cardinals player this season. Molina produced his streak from May 1-27. ... The Mets were shut out for the fourth time this season while the Cardinals blanked an opponent for the ninth time.