Peavy (9-8) ended a personal 0-3, 8.83 slump in his last four starts. The right-hander allowed just two hits, walking four and striking out five. Peavy left with a 6-0 lead courtesy of Nevin, who had an RBI single in the first inning and a three-run homer in the fifth.
The Padres bullpen nearly gave it away. After Luther Hackman pitched a scoreless eighth, Mike Matthews could not get an out in the ninth, allowing three runs. Jay Witasick gave up another run before striking out Marlon Byrd to end it.
It was the first regularly scheduled doubleheader since 1985 at Veteran Stadium. The Phillies had swept their first two doubleheaders this year and had a four-game winning streak snapped.
Phillies starter Randy Wolf (11-6) came in with a 4-1 career mark against the Padres but did not have his best stuff. Wolf gave up six runs - four earned - with five hits and a season high-tying five walks in five innings. "He did not have real good rhythm. He did not have his control," Phillies manager Larry Bowa said. "Peavy pitched good. He had a good slider, a good change. He has really good stuff."
In the first, Gary Matthews Jr. and Mark Loretta walked around an out. They moved up on a wild pitch and both scored on Nevin's single, which was bobbled by right fielder Bobby Abreu. Brian Buchanan opened the second with a single and stole second. One out later, Lou Merloni singled and stole second, allowing Buchanan to scor on the play when shortstop Jimmy Rollins misplayed the throw from catcher Mike Lieberthal.
With two out in the fifth, Sean Burroughs and Loretta singled and Nevin launched his third homer of the season. He had been sidelined for the first half of the season with a separated shoulder.
Meanwhile, Peavy was cruising. After Placido Polanco singled with one out in the third, no Phillie got a hit until the Padres went to their bullpen.
In the ninth, Mike Matthews gave up singles to Abreu, Lieberthal and Tyler Houston, plating a run. Witasick came on and got pinch-hitter Tomas Perez to bounce into a force play before Rollins singled home a run. Witasick threw away a pickoff attempt, allowing Perez to score and Rollins to race to third. Pinch-hitter Ricky Ledee lifted a sacrifice fly to empty the bases, and Byrd - who has a 14-game hitting streak - struck out.
Game 2: Phillies 10, Padres 4
Marlon Byrd and Placido Polanco are providing a true one-two punch for the Phillies. Byrd and Polanco combined for four hits, five runs and five RBI as the Phillies routed the San Diego Padres, 10-4, to gain a split of their doubleheader.
Batting first and second in the order, Byrd and Polanco are riding long hitting streaks. Byrd has hit in a career-high 15 straight games while Polanco has hit in nine, batting .500 (17-for-34) with 14 RBI and 11 runs.
"It's just great to have your 1-2 guys hitting well," Byrd said. "It is just great timing. Sometimes it happens and sometimes it does not. Placido has picked me up when I have not been hitting."
After a 6-4 loss in the opener, Byrd was 2-for-4 with two runs and two RBI and Polanco was 2-for-3 with three runs and three RBI in the nightcap as Philadelphia improved to 5-1 in doubleheader games this season.
"Losing two, we would drop a game and a half, so we had to go out there and get a win," Phillies manager Larry Bowa said.
Terry Adams pitched two scoreless innings before Rheal Cormier (3-0) worked two hitless innings for the win. Jose Mesa and Dan Plesac finished up as Philadelphia's bullpen allowed one run in nine innings in the twin-bill. Cormier has not allowed a run in his last 15 innings.
With one out in the first, Polanco and Jim Thome walked and Bobby Abreu singled home a run. The Padres tied it in the second on an RBI double by Gary Matthews Jr., but the Phillies answered in the bottom half on Polanco's RBI single.
"Everybody from the leadoff hitter until the last guy, pinch-hitters, we are making it real tough on the opposing pitcher," Polanco said. "That is going to take us a long way."
San Diego again tied it as Mark Kotsay doubled, stole third and scored on Mark Loretta's groundout. The Padres took the lead on Miguel Ojeda's RBI single before the Phillies erupted in the bottom half. With runners at the corners and one out, Byrd singled in a run to chase Roa. Polanco greeted Scott Linebrink with a two-run triple that made it 5-3 and scored on Thome's groundout.
Roa, who started Philadelphia's home opener earlier this year, gave up five runs, six hits and three walks in 3 1/3 innings.
In the eighth, Byrd had an RBI single and Polanco walked before Abreu stroked a two-run single and Ricky Ledee added a run-scoring single.
Ojeda homered off Mesa in the ninth.