Bolstered by a three-run homer by Ryan Doumit and Freddy Sanchez's solo shot, Snell (7-12) allowed only a solo homer before his calf tightened and he had to come out of his final start of the season.

"I just wanted to finish the season strong and that's what I did," Snell said. "There's no guessing about it, I finished stronger than I started."

Snell had not allowed a hit before Nick Hundley homered with two outs in the fifth inning to tie the game at 1. The right-hander went 3-2 with a 4.26 ERA in his seven starts since Aug. 19.

"I'm not going to say I'm going to go and rebuild and think about it for this offseason," Snell said. "I'm done thinking about that. I have to come back strong."

Doumit's 15th homer to right off reliever Mike Ekstrom (0-2) broke a 1-1 tie in the sixth.

Sanchez, who had three hits, homered with one out in the first off rookie Josh Geer, who also left the game after five innings with tightness in his right elbow.

Snell, who struck out five and walked one, won for the third time in four road starts.

"I left everything on the field. People can judge that performance," he said.

"He's been making a lot of progress, especially the second half," said Pittsburgh manager John Russell. "He's had some really good outings where he had good innings and one inning he didn't. It was a good note for him to end on."

Snell, who came into the game with a 6.48 road ERA, is 4-8 in 17 road starts.

"He's got good stuff," Padres manager Bud Black said. "I think today he got the ball more in the strike zone probably more than he has."

Matt Capps, the fifth reliever, pitched the ninth inning for his 21st save in 26 chances.

The win was only the Pirates' third in their last 16 games at San Diego, including a seven-game losing streak.

Pittsburgh, which had lost four straight, was swept at Milwaukee in the first three games of a six-game road trip that ends the season.

San Diego (62-98) must win one of its final two games against the Pirates to avoid the franchise's fifth 100-loss season. The Padres equaled their most losses since the 2003 club went 64-98.

The Pirates broke the 1-all tie after Nate McLouth and Sanchez started the sixth inning with singles before Doumit's home run.

Luis Rodriguez's RBI single and a double play pushed across two runs for the Padres in the bottom of the inning to cut the lead to 4-3.

Pirates reliever John Grabow escaped a bases-loaded jam in the eighth when he struck out Kevin Kouzmanoff.

Pittsburgh added two runs in the ninth on Brian Giles' error when he dropped a routine fly ball for the final out.

Geer allowed one run on three hits before being forced from the game. Geer has lasted five innings in four of his five major league starts.

"It's been tight since my last start," said Geer about his elbow. "I didn't feel it too much out there but each inning it felt a little worse. In the fifth inning, I really started feeling it there. I think it's just a strain."

Notes: Pirates OF Nyjer Morgan, who suffered a mild left hamstring in Thursday loss at Milwaukee, did not play Friday and is done for the season, according to manager John Russell. ... Giles, a former Pirate, committed his seventh error.