PITTSBURGH — Proof that baseball is indeed a very funny game: The Atlanta Braves suddenly can’t win on the road. And Jason Bay, usually a good road hitter, is discovering a power stroke at home.

Tom Gorzelanny shook off Mark Teixeira’s two-run homer in the first inning to shut out Atlanta during the rest of his 7 1-3 innings, Bay homered and the Pittsburgh Pirates extended the Braves’ road woes with a 5-2 victory Saturday night.

Bay doubled and scored in the second inning, then followed Jason Michaels’ leadoff single with a go-ahead, two-run homer to left-center in the fourth off Chuck James (2-2). Ronny Paulino added a two-run double in the sixth and drove in three runs during Pittsburgh’s fifth consecutive victory.

Bay, bothered by a sore knee the last two seasons, is healthier and it shows. He has six homers in PNC Park, where he hit only seven of his 21 homers last season, and is running and fielding much better.

“It’s nice when you see the ball well in your own ballpark, where you play 81 times,” Bay said. “I don’t have an answer for it, but I’m not going to question it.”

Going into this season, 72 of Bay’s 118 career homers were on the road.

Almost as important to Bay as the homer that put the Pirates up 3-2 was his steal of third in the second inning, the front end of a double steal. The stolen base allowed Bay to score on Paulino’s sacrifice fly.

“I didn’t have a first step last year or the last part of the year before that, and that’s the biggest thing out there running and playing defense,” Bay said. “The last two years, I’d get on base and never think about it (running).”

The Braves, who came to Pittsburgh after sweeping a six-game homestand against San Diego and Cincinnati, lost their sixth in a row away from home and are a major league-worst 4-13 on the road. Their home record is 14-4.

Teixeira felt Atlanta caught a bad break in the fourth when James appeared to pick off Michaels at first, only to have umpire Mike Estabrook call him safe. Bay then hit his seventh homer.

“It was a terrible call, he missed it,” Teixeira said. “Umpires miss calls. It didn’t cost us the game, it hurt, but at the same time they’re going to miss calls.”

Gorzelanny (3-3), skipped over for a start because of a lower back problem, cruised after a difficult first inning in which Omar Infante doubled and, after a pair of force-play grounders, Teixeira hit an 0-1 pitch deep into the left-field seats for his fifth homer.

Gorzelanny allowed only five singles after that, never allowing a runner past first base as the Pirates’ defense turned three double plays. The Pirates turned a fourth double play after Franquelis Osoria replaced him with one on and one out in the eighth.

“In the first, I was trying to prove to myself I was feeling good,” Gorzelanny said. “That (homer) was an eye-opener. I was trying to do too much and I left a pitch over the heart of the plate and anybody can hit that. I told myself after that to keep the ball down and let them hit it into the ground.”

Gorzelanny struck out four and walked two, following up on a 13-1 win over the Mets on April 30 in which he gave up one hit over five shutout innings until leaving because of the back problem.

Gorzelanny, who walked 12 in his previous two starts and 27 in his first 27 1-3 innings this season, was much sharper while throwing 60 of 92 pitches for strikes.

Matt Capps pitched the ninth for his ninth save in as many opportunities and his 27th in 29 chances since becoming the Pirates’ closer last June 1.

James, recalled from Triple-A Richmond to make his fourth start this season, struck out seven but walked four while giving up five runs and five hits over six innings.

“I went back and looked at all the hits I gave up,” James said. “They were belt high down the middle. It’s tough to win that way. To be successful up here, I have to hit my spots and put the ball on the corners.”

Notes: Chipper Jones went 0-for-3 with a strikeout and a double-play grounder against Gorzelanny after previously being 4-for-5 against him. ... Bay went 2-for-4 and has seven hits in his last 13 at-bats. ... Michaels, acquired in a trade Thursday with Cleveland, went 3-for-4 with three singles and scored twice in his first Pirates start. Nate McLouth, hitting .315, didn’t start in center field for the first time this season. ... The Braves placed reliever Buddy Carlyle on the 15-day disabled list with a strained neck.