Valentin hit a pinch-hit, two-run homer in the bottom of the ninth inning to lift the Reds over the Arizona Diamondbacks 5-4 Sunday.
Austin Kearns hit a pinch-hit single off Arizona closer Jose Valverde with one out in the ninth. Valentin followed with his first career pinch-hit drive.
"Every time we've faced him, he's hit the first pitch, and he's looking to pull it," Arizona manager Bob Melvin said. "It was a (split-finger fastball) that Valentin hit. I don't second guess the pitch. I'm sure (Valverde) doesn't feel great about the outcome."
Valentin's first homer of the season snapped Arizona's winning streak at five games and the Reds' losing streak at three.
"In a situation like that, you look for their best pitch," said Valentin, whose pinch-hit single gave Cincinnati a 3-2 win over St. Louis on May 2. "I've faced (Valverde) before, and the split is what he threw. I was just looking for something hard and middle in that I could get a good swing on."
David Weathers (2-2) allowed two hits in two scoreless innings to get the win as the Reds avoided a sweep of the three-game series. Valverde (2-2), who refused comment after the game, blew his second save in 16 opportunities.
The Diamondbacks wasted a strong major league debut by Enrique Gonzalez, who allowed three hits and one run in six innings. The right-hander struck out four and walked one.
Ryan Freel led off the first inning with a home run off Gonzalez, who was called up from Triple-A Tucson on Friday. Freel's first homer of the season snapped the Reds' streak of consecutive scoreless innings at 21.
"I was nervous," said Gonzalez, who didn't allow a runner past first base after giving up Freel's homer. "I'd never pitched in front of that many people before. I was excited. I just wanted to keep the ball down in the zone and put the ball in play."
Playing for the first time since Monday and starting in right field for the first time all season, Freel also threw Shawn Green out at the plate to end Arizona's eighth inning. Green was trying to score on Johnny Estrada's single.
"Winning like that should be a tremendous lift, because everybody contributed," Reds manager Jerry Narron said.
Luis Gonzalez had a two-run double and Conor Jackson added an RBI single as Arizona led 4-1 after six innings.
Jorge Julio pitched a scoreless seventh for the Diamondbacks but Scott Hatteberg hit a two-run homer off Brandon Lyon in the eighth to get Cincinnati within one. Hatteberg's third homer of the season bounced off the top of the right-field fence.
Reds starter Bronson Arroyo, who gave up a career-high 11 hits in six innings of a 3-1 loss at Arizona on May 6, continued to have problems with the Diamondbacks. He allowed seven hits and four runs with three walks and six strikeouts.
Narron was ejected by plate umpire Larry Vanover in the bottom of the seventh for arguing balls and strikes. The ejection was Narron's second of the season. ... Freel's leadoff homer was the second of his career. ... Reds C David Ross bunted for a hit to lead off the eighth and extend his hitting streak to a career-high six games. ... SS Felipe Lopez was caught stealing in the third. Lopez already has a career-high 16 stolen bases, none in three tries since May 11.