Hairston hit a three-run homer with two outs in the ninth inning Wednesday night, lfiting the Padres over the Pittsburgh Pirates 5-3. The win increased San Diego's lead in the NL wild-card race to 2½ games over Philadelphia, which lost 2-1 in 10 innings at St. Louis.
Hairston, acquired in a trade with Arizona on July 27, also hit a game-winning, solo homer to give San Diego a 4-3 win in 10 innings on Aug. 3 against San Francisco. He entered that game as a defensive replacement and hit a three-run homer in the eighth to tie the game.
"He's made a couple of big swings since he's been here," Padres manager Bud Black said.
Hairston's homer gave San Diego its sixth straight win and allowed the Padres to stay one game off the NL West lead behind Arizona.
Hairston hit an 0-1 slider from Matt Capps (4-7) over the left-field wall. He had been just 5-for-30 (.167) with two outs and runners in scoring position this season.
"I thought I hit it really good," Hairston said. "I know I don't have that much power. In this ballpark, you never know unless you hit it really well. I've seen so many balls in this park come up short."
The timely hit rescued the Padres, who had been held in check after scoring a pair of first-inning runs. San Diego had just three singles from the second through the eighth innings.
"There is no quit in this team," said Adrian Gonzalez, who got the Padres' ninth-inning rally started with a double. "We've won a number of games like this and we believe in each other."
Gonzalez's double off the left-field wall nearly cleared the fence with one out. Kevin Kouzmanoff followed with a two-out walk before Hairston with his eighth home run, and was met by a wild celebration at home plate.
"It just wasn't the right pitch," Capps said. "I went against every instinct I had and got beat by something that wasn't my best pitch. That's the hard part."
Cla Meredith (5-6) pitched a perfect ninth inning for the win.
"We did everything we could do," Pittsburgh manager Jim Tracy said. "Unfortunately, (Capps) was just an out away from a fabulous save."
Pittsburgh lost its fifth straight game.
"I wanted to see a pitch because I know he had good stuff," Hairston said. "But you really can't get too aggressive in that situation."
All-Star Chris Young started for the Padres and was in danger of losing his fifth straight decision. He gave up three runs and five hits over six innings.
The right-hander was 9-3 and led the majors with a 1.82 ERA when he left a start on July 24 after two innings with an injured side. He went on the 15-day disabled list and since coming back on Aug. 9, Young has gone winless in eight starts with a 5.61 ERA in those games.
Ian Snell limited San Diego to one earned run and four hits in seven innings and said he left with a sore arm. He gave up two runs in the first inning, but faced only one batter over the minimum in the next six innings.
San Diego scored twice in the first to erase the Pirates' 1-0 lead. Brian Giles led off with a double and went to third on a passed ball. After Mike Cameron walked and stole second, Gonzalez blooped a two-run single.
Pittsburgh went ahead 3-2 in the third after Snell reached on a fielder's choice. Morgan was hit by a pitch, McLouth doubled in a run and Freddy Sanchez hit a sacrifice fly.
- Young's last win was a 1-0 decision over Philadelphia on July 19.
- Pirates SS Jack Wilson was not in the starting lineup after leaving Tuesday night's game with tightness in his right hamstring. Cesar Izturis replaced Wilson.