Joey Votto's bases-loaded walk in the sixth inning brought home Zack Cosart with the winning run, and Cincinnati claimed a 5-4 decision over Pittsburgh in the middle test of a three-game series.
Cozart and Brandon Phillips both finished with two hits, an RBI and a run scored for the Reds, who have won four of their last five, including the first two in the set.
Mat Latos (9-3) allowed four hits and three runs -- two earned -- over five innings for the win. Aroldis Chapman posted his 23rd save with a scoreless ninth, but worked out of a two-on, no-out jam to wrap up the contest.
"If we had gone a whole lot longer, he might not have been able to come back," Reds manager Dusty Baker said of his starter. "As it was, he was at 100 pitches in the fifth. He was really at about 125-130, including what we threw underneath to stay warm."
Andrew McCutchen collected four hits including a solo homer, and Garrett Jones also went deep for the Pirates, losers of three straight and seven of 10.
A.J. Burnett (4-7) was charged in the setback with 10 hits and five runs -- two earned -- in 5 2/3 frames.
"We fought to get on base and to give ourselves opportunities to win the game," noted Pirates manager Clint Hurdle. "The effort is there, but the challenge is to meet the demands of the game and overcome them."
Cozart began the home sixth with a base hit, then advanced on a one-out pinch- single from Cesar Izturis. Chris Heisey's walk loaded the bases, then Votto also drew a base on balls which forced Cozart home to make it 5-3 for Cincinnati.
Travis Snider's pinch-hit double cut Pittsburgh's deficit to one in the eighth.
In the ninth, McCutchen reached on a dribbler to the left of the mound and took second on Chapman's errant throw. Pedro Alvarez was at first and McCutchen at third after Cozart botched a grounder, but Chapman bore down and retired the next three batters to lock up the one-run victory.
"Those guys, they battle until the end. We put up a big lead, and they never give up," said Reds catcher Devin Mesoraco of the Pirates. "They always come back on us. It was definitely a battle, but guys did their job, and we got through it."
After a 77-minute rain delay in the middle of the opening inning, the Reds dented Burnett for four runs thanks to a Jordy Mercer error which allowed Shin-Soo Choo to come home, an RBI single from Phillips, sacrifice fly from Cozart and run-scoring double by Mesoraco.
"We all have our routines, and that was nowhere close to it," groused Burnett.
Jones began the second with his ninth homer of the season, and later in the inning with runners on first and second, Clint Barmes scored when Cozart flubbed his throw to first on a Jose Tabata grounder.
"That's very uncharacteristic of our team, especially from Cozart. He just doesn't make any mistakes," said Baker.
Burnett killed a rally by fanning with the bases loaded and two down in the third, but McCutchen's two-out solo homer in the fourth brought the Bucs within 4-3.
Cincinnati's victory evened the season series at six wins apiece, with the hosts evening their home record at 3-3 against Pittsburgh this year ... The Pirates bullpen held the Reds hitless with one walk and five strikeouts in the final 2 1/3 innings ... Bengals defensive tackle Geno Atkins threw out the ceremonial first pitch.