Starling Marte's fifth-inning RBI single was the go-ahead run in a 3-1 Pittsburgh victory over Cincinnati in the middle test of a three-game series.
Garrett Jones and Jose Tabata added a run-scoring double each for the Pirates, who have taken the first two in the set and have won four of their last five overall.
Jeff Locke (1-1) walked four and did not strike out a batter in his five- inning outing, but allowed just four hits and one run to outduel counterpart Johnny Cueto.
"I let the defense make some plays and threw some really good pitches in some counts when I was behind," Locke said. "I had a hard time getting strike one over today."
Cueto yielded a run on two hits, but departed after 4 1/3 frames with a right arm injury. Alfredo Simon (0-1) was charged in defeat with three hits and two runs in two relief innings.
"It's not anything in the elbow or anything in the shoulder," Reds manager Dusty Baker said. "It's actually in the belly of the triceps. We're going to send him tomorrow to get examined."
Zack Cozart had three hits, but his homer was the lone offense for the Reds, who have dropped four straight.
Cueto fanned Pedro Alvarez to begin the fifth, but left the game in favor of Simon while shaking and holding his right arm. Travis Snider singled, moved to second on a Clint Barmes hit, then advanced to third on a Josh Harrison fly out before scoring on Marte's pinch single for a 2-1 Pirates lead.
The Bucs picked up an insurance run in the seventh, as Alvarez worked a leadoff walk, moved up on a Snider groundout, went to third when Barmes fouled out and came in on Tabata's pinch double.
Mark Melancon shut the door in the eighth and Jason Grilli stranded a runner on second in the ninth, ending the game on a pop out from Todd Frazier.
Cozart's one-out solo shot put the Reds on the board in the third, but Jones doubled home Andrew McCutchen in the fourth to tie the score.
Saturday's victory gave the Pirates back-to-back wins against the Reds in Pittsburgh for the first time since Sept. 23-24, 2011 ... Coming into the contest, Pittsburgh's pitching staff have held the opponents to a .215 batting average, the third-lowest mark among National League teams behind Los Angeles (.206) and Atlanta (.212) ... Marte fanned in the first inning, snapping his streak of six consecutive games with a first-inning hit ... Melancon has not allowed a run in seven innings over seven appearances this season.