ST. LOUIS -- The last time the Cincinnati Reds needed a replay reversal in a big September game at Busch Stadium, they waited too long to ask for one and lost a game on an incorrect call that couldn't be changed.

This time, Bryan Price made the request in time and it led to the big inning that damaged the St. Louis Cardinals' playoff hopes.

Joey Votto's RBI single and Eugenio Suarez's grand slam scored five runs right after the fifth inning was extended by a reversed call in Cincinnati's 6-0 win Wednesday night.

"I think our video guy (Bo Thompson) deserves a couple of those RBI," joked Price.

With two outs and men at first and second in the fifth, Zack Cozart grounded Ryan Sherriff's pitch up the middle. Shortstop Paul DeJong made a diving stop and flipped to Kolten Wong as pitcher Tyler Mahle reached the bag.

Second-base umpire Gabe Morales punched Mahle out for the apparent third out. But Price quickly heard from Thompson, who phoned the dugout to tell him to ask for a replay.

After a review lasting 1:18, Mahle was ruled safe. Instead of the inning being over, the bases were loaded and Votto, arguably the toughest out in baseball, was batting. His first-pitch single to left field scored Jose Peraza for a 2-0 lead.

Three pitches later, Suarez broke the game open when he became the fourth Red to hit the 25-homer plateau.

Feasting on a fat 1-1 slider, Suarez ripped it 383 feet into the Cincinnati bullpen in left for his second career slam. It was also the Reds' seventh slam of the year and their 200th homer overall as they improved to 63-83.

"I was just looking for something in my strike zone," Suarez said. "I just always want to put my best swing on it and that was the perfect pitch he threw me right there. So that was really nice."

That, along with a gutsy job of pitching around a lot of traffic during his five innings, earned Mahle (1-2) his first win in his fourth big-league outing. The right-hander gave up four hits and three walks, striking out four.

St. Louis (76-69) stranded seven runners in the first three innings, leaving the bases loaded in the second. An offense that scored 13 runs on Tuesday night, mostly with timely two-out hits, couldn't produce a single marker 24 hours later.

It resulted in just the Cardinals' third loss in 12 September games, and a costly one at that. They fell into third place in the National League Central, three games behind the first-place Chicago Cubs and a half-game behind Milwaukee.

"We got into situations where we were putting the pressure on and needed the big hit," St. Louis manager Mike Matheny said. "The kid made good pitches when he needed to."

Jack Flaherty (0-1) was able to match Mahle for 4 1/3 innings, with the exception of his second pitch of the night. Leadoff man Jesse Winker took that one over the wall in right field, a 395-foot shot that was his fifth homer of the year.

Flaherty blamed himself for the fifth inning. He failed to cleanly field Tucker Barnhart's smash up the middle, turning a potential double play into an out. Flaherty then plunked Mahle with his 70th and last pitch of the night.

The final line in Flaherty's third big league start: 4 1/3 innings, four hits and three runs, two walks and three strikeouts.

Minutes after the game, Price was reminded about a 4-3 loss last September to the Cardinals that ended on Yadier Molina's two-out RBI double in the ninth. The ball appeared to bounce off signage behind the left-field wall but was ruled in play by the umpires.

Price didn't get instructions to challenge until the umpires had left the field, and he ran down the ramp to their locker room in an unsuccessful attempt to change their mind.

"The commissioner told me it was a poor decision on my part to wait too late," he said, smiling. "What about the four umpires who didn't see the ball bounce out of play?

"But that play doesn't happen tonight without Tyler Mahle hustling and beating it at second, and Bo Thompson telling us we should challenge."

NOTES: St. Louis activated 3B Jedd Gyorko (right hamstring) from the 10-day DL. Gyorko will be available for the time being as a pinch-hitter. He was injured Aug. 26 while rounding third base against Tampa Bay. ... Cincinnati 2B Scooter Gennett (left hand inflammation) wasn't in the lineup. Gennett left Tuesday night's game before the bottom of the fifth inning after injuring himself while hitting a foul ball in the fourth inning. ... Cardinals CF Dexter Fowler (left knee) isn't sure when he'll be able to return from an injury suffered in a collision with the wall in the seventh inning Saturday night. He missed his third straight start Wednesday.