Wheeler (10-9) allowed one run over six innings to earn the victory, the 13th consecutive start in which he has allowed three or fewer earned runs. He has worked a career-high 170 1/3 innings with three weeks yet to play. A year ago, he was shut down in September to keep his season innings total at 168 2/3.
"It is late in the season and I'm starting to wear down a bit, but I'm learning how to pitch through it," Wheeler said. "Honestly, I feel good."
"We will keep a close eye on him," Mets manager Terry Collins said. "We want him to finish the season healthy. It's been pretty impressive, how he's maintained it. He had great energy today and really, really good stuff."
Mejia survived a wild ninth inning in which Cincinnati scored two runs, the first four Reds hitters blasted his pitches into the outfield and the Mets were on the short end of an overturned call. That may seem like small potatoes, however, to a guy who has already dealt with a bunion, a forearm contusion, a blister on his throwing hand, calf soreness, multiple lower back issues and a hernia that will require surgery after the season.
"I feel fine," Mejia said after his 24th save. "[Staying healthy] is very important. If I'm healthy, I can help my team."
The Reds scored twice off Mejia in the ninth to reduce a 4-1 lead to 4-3 and reloaded the bases before Mejia struck out cleanup hitter Devin Mesoraco to end the game. The Mets thought the game had ended when Todd Frazier grounded out, but Cincinnati manager Bryan Price challenged the play, and the replay umpires ruled Frazier safe after a three-minute and eight-second review.
"Our guy didn't think there was enough to overturn it," Collins said. "[The review] might have given [Mejia] a chance to refocus himself. He made some good pitches to Mesoraco."
Anthony Recker's two-run home run in the sixth inning off Mat Latos (5-5) broke a 1-1 tie and gave the Mets a 3-1 lead. Curtis Granderson added a solo homer, his 18th, in the eighth.
Recker, batting in the No. 8 spot, crushed a 412-foot home run that smacked off the facing of the second deck in left field. The Mets' backup catcher has 13 homers in his brief Major League career, and 10 have either tied the score or given New York the lead.
"I'll just call it luck; I just tend to get lucky in big situations," Recker said. "In that situation, with the pitcher on deck, I didn't know if they'd give me much to hit or not."
Wheeler induced a 1-2-3 double-play ground ball from Brandon Phillips with the bases loaded in the fourth and struck out Frazier and Jack Hannahan to end the fifth and sixth innings, respectively, with a runner at third base.
"Zack is definitely starting to prove he's a front-end-of-the-rotation kind of guy," Recker said. "He's finding his niche."
Recker's go-ahead homer followed a surprising bit of good fortune earlier in the inning for the Mets, who never really threatened against Latos during the first five innings.
Reds center fielder Billy Hamilton appeared to have tracked down Wilmer Flores' long drive to the warning track in center field, but the ball hit off the top of Hamilton's glove, just the second error of the season for the speedy rookie. Granderson followed with an RBI single to the right-field corner that tied the score at 1.
"I thought it was hit softer than what it was, so at the last minute, I saw the wall, and I took a peek, and that one little peek did it," Hamilton said. "But no excuses; I missed it. It was my fault."
The Mets have taken two of three from Philadelphia, Miami and Cincinnati during their last three series.