PITTSBURGH – Jason Bay’s 100th home run for the Pirates was one of his shortest, barely nudging itself over the right-field wall. Regardless of the length, it illustrated how one of the NL’s most consistent hitters is trying to get even better.

Bay hit a two-out homer in the eighth, an inning after Pittsburgh tied it on Ronny Paulino’s double, and the Pirates came back from a two-run deficit to beat the Chicago Cubs 3-2 Monday night.

Bay’s opposite-field shot off Michael Wuertz (0-1) was his fourth of the season and his 100th with the Pirates. Bay is the 20th player in club history to hit that many.

“Honestly, the last thing I was thinking there was home run,” said Bay, a starting NL outfielder in the All-Star game last season. “That’s probably what helped me get it. I didn’t know if it had enough legs; I had to give it a little oomph going around the bases, but I’ll take it.”

Wuertz left a slider up in the strike zone, a pitch he knew he couldn’t make against a hitter such as Bay.

“It’s disappointing to lose a game that way, the way we battled all night,” Wuertz said. “It just goes to show you what one pitch can do.”

That Bay went the opposite way with the pitch shows the maturity he is developing. He wasn’t a bad clutch hitter before this season; he was a career .299 hitter with runners in scoring position, but he has become more conscious of taking good at-bats in key situations.

“It’s a different mentality than going up there in the second inning with nobody on and the game 0-0,” Bay said. “It’s a different at-bat, a little more intense, and I’m still learning. You’re not going to do it every single time, but you still have to make the conscious effort to do it. I’m doing a better job of putting balls in play and using the whole field.”

Salomon Torres, the Pirates closer who was scored upon in six of his previous eight appearances, pitched a scoreless ninth for his eighth save in 11 opportunities. Matt Capps (2-0) won it by pitching the eighth.

Cubs starter Rich Hill limited the Pirates to two runs over seven innings and helped himself with an unlikely run-scoring double, but couldn’t hold a 2-0 lead.

“To sneak in there and take this one, that was big,” the Pirates’ Adam LaRoche said.

Hill went a night later than expected after the Cubs’ scheduled game in St. Louis was called off Sunday because of Cardinals pitcher Josh Hancock’s death. He walked only one but it hurt him as Jose Bautista came around to score on Paulino’s tying double.

The Cubs stranded five runners in the final three innings, with reliever Jonah Bayliss retiring Aramis Ramirez on a fly ball with the bases loaded and two outs in the seventh.

“Late in the game we had numerous chances and left them stranded,” said Cubs manager Lou Piniella, whose team is 0-6 in one-run games. “They get a clutch home run from Bay in the eighth, and that was the difference.”

The Pirates could have anticipated Hill’s strong pitching; he was 1-0 with a 1.26 ERA against them in two starts, striking out 20 and walking four.

The surprise was Hill driving in the first run of his career in 47 at-bats on an opposite-field double down the third-base line in the second.