Had Brayan Pena not been nursing a tender left hamstring, Mesoraco might not even have been in Sunday's lineup. Pena had been the starting catcher for 20 of right-hander Johnny Cueto's previous 24 starts this season.
"I figured I would be starting with Brayan [injured] and the off-day Monday," Mesoraco said. "We're going to need him healthy pretty quick."
Miami starter Brad Hand (2-4) had matched Cueto into the fifth inning, when the game was tied at 2-2 after solo homers from Giancarlo Stanton and Casey McGehee sandwiched around a two-run homer from Mesoraco. But then the left-hander lost the strike zone.
Hand walked Ramon Santiago to lead off the frame, then Zack Cozart followed with a single through the left side. Cueto's sacrifice moved the runners up. Kris Negron was retired on a shallow fly ball to center, but Jay Bruce worked the count full before walking to load the bases. Todd Frazier also walked on a 3-2 pitch, forcing in the go-ahead run.
Up came Mesoraco, who turned on Hand's 2-1 pitch and sent the ball sailing into the left-field seats. Mesoraco's 20th home run of the season widened the gap to 7-2.
"I'm just up there trying to stay calm, get the pitch I'm looking for and don't miss it," Mesoraco said.
He certainly appeared calm until arriving at a dugout full of high-fiving teammates.
"I'm definitely excited, but I'm not going to jump around or skip or fist-pump or anything like that," Mesoraco said.
Some free tutoring doesn't hurt, either. Mesoraco recalled a conversation with Hall of Fame catcher Johnny Bench that had taken place a day earlier.
"I picked his brain a little," Mesoraco said. "He suggested I relax my hands a bit more."
Chris Sabo (1993) was the last Reds hitter with three grand slams in a season. Mesoraco's six RBIs marked a career high.
Sunday's offensive outburst came at an opportune moment for the Reds, who had scored two runs or fewer 11 times in 22 games since the All-Star break.
Cincinnati grabbed its first lead of the series, 2-1, when Mesoraco's two-run shot bounced off the roof of the Reds bullpen in left-center in the first. Bruce, the only left-hander in Cincinnati's starting batting order, had singled two batters earlier.
Cueto (14-6) made the lead stand up, as he extended to 12 his streak of starts not allowing more than three earned runs. Even a hard bouncer off his right rib cage in the third inning didn't slow down Cueto, who struck out nine over eight innings of five-hit, two-run ball.
"It was itching a lot," Cueto said through interpreter Tomas Vera when asked about the injury.
Manager Bryan Price's club was certainly itching for a win.
"That was a game we needed to win," Price said. "We needed to get a good feeling back."