First pitch in the big leagues: home run.

Mark Saccomanno quickly made a name for himself Monday night and helped the surging Houston Astros creep closer into playoff contention.

Called up from the minors earlier in the day, Saccomanno arrived at the ballpark minutes before the opening pitch. He pinch hit for starter Alberto Arias in the fifth inning and drove Ian Snell’s first delivery the opposite way into the right-field bullpen to lead Houston past the visiting Pittsburgh Pirates 3-2.

“He walks up there like he isn’t nervous at all. And he just hits it out,” Astros manager Cecil Cooper said.

The solo shot snapped a scoreless tie and triggered a three-run inning for Houston, which has won three straight and 11 of 12 to move 10 games over .500 for the first time this season. Suddenly, the surprising Astros are only five games behind Milwaukee, which leads the NL wild-card standings.

Saccomanno became the 22nd player to hit a home run on his first pitch in the majors.

Kevin Kouzmanoff was the last to do it, according to the Elias Sports Bureau. He accomplished the feat for Cleveland on Sept. 2, 2006, becoming the only big leaguer to hit a grand slam on his first pitch.

“I went up there very nervous. I don’t even remember it, my legs were so weak,” Saccomanno said. “It was a great feeling to hit it out. It was like a dream.”

The 28-year-old Saccomanno batted .297 with 27 homers and 84 RBIs for Triple-A Round Rock this season. He was in Austin, Texas, at 2:30 p.m. on Monday when he got the call to join the Astros, so he hopped a flight to Houston at 4:30 and arrived just in time.

“I didn’t get a chance to get any swings before the game,” Saccomanno said. “So I went down to the batting cage in the second inning with (coach) Dave Clark. I was thinking about what to do and I said if I got in I might take a pitch. He said, ‘If you do, I’ll fine you,’ and I knew he would.”

After Saccomanno’s homer, the next four batters got hits — including RBI singles by Miguel Tejada and Lance Berkman.

“Who would have thought that a guy coming off the bench would do that?” Snell said. “I threw him a fastball down and away and he went and got it.”

The last Houston player to homer in his first career at-bat was Charlton Jimerson on Sept. 4, 2006, at Philadelphia.

“He showed up about 6:30 and jumped in a uniform and had a pretty good start,” Cooper said. “He really made it big. We were looking a little stale until he got that hit.”

Arias (1-0) gave up two hits and struck out six in five impressive innings. It was his first major league start after 18 relief appearances with Colorado. He got the ball in place of Brandon Backe, scratched because of soreness in his arm during a bullpen session Saturday.

LaTroy Hawkins pitched a scoreless eighth. He has not allowed a run in 16 games since coming to the Astros in a trade with the New York Yankees on July 30.

Jose Valverde worked the ninth for his NL-leading 41st save in 47 attempts. He has recorded saves in a club-record 14 straight appearances.

Snell (6-11) went six innings, allowing three runs and six hits.

Phillies 8, Marlins 6

At Philadelphia, Jayson Werth hit a three-run homer and Jimmy Rollins had three hits and three steals. The Phillies closed within 11⁄2 games of first-place New York in the NL East.

Joe Blanton (2-0) pitched five shaky innings to earn his first win since Aug. 2, and Brad Lidge finished to remain perfect in 35 save chances. Lidge put the tying runs on base before escaping the jam by striking out Wes Helms and Jorge Cantu.

Padres 4, Dodgers 0

At San Diego, Adrian Gonzalez hit a two-run homer off former teammate Greg Maddux (7-12) and the last-place Padres snapped the NL West-leading Dodgers’ eight-game winning streak.

Cha Seung Baek (5-9) combined with two relievers to four-hit the Dodgers, who have a 11⁄2-game lead over Arizona. Los Angeles leapfrogged the Diamondbacks into the division lead with a three-game weekend sweep at Dodger Stadium. Maddux dropped to 1-3 with the Dodgers.

Giants 6, DiamondBacks 2

At San Francisco, Tim Lincecum boosted his bid for the NL Cy Young Award, handing Arizona its fourth straight defeat.

Lincecum (16-3) struck out nine in 8 1-3 innings, the longest outing of his career, and lowered his NL-leading ERA to 2.54. Bengie Molina hit a three-run homer off Yusmeiro Petit (3-5).

Reds 5, Brewers 4

At Milwaukee, Jeff Keppinger’s double capped a three-run rally in the ninth against Brewers closer Salomon Torres (6-5).

Milwaukee’s wild-card lead was cut to three games over Philadelphia with 18 to play. The Brewers and Phillies play a four-game series beginning Thursday in Philadelphia.

Francisco Cordero earned his 28th save in 34 chances.