HOUSTON — The Houston Astros took care of the Pittsburgh Pirates, then hurried back to the clubhouse to see what their rivals were doing.

Lance Berkman hit a three-run homer and Randy Wolf shut down Pittsburgh after a shaky first inning as the Astros continued their second-half surge with a 9-3 victory Tuesday night.

Berkman had an RBI double and scored three runs for the Astros, who have won four straight and 12 of 13. Houston's 34-16 record is the best in the majors since the All-Star break and the Astros are emerging as a factor in the NL wild-card race.

Houston came into Tuesday's game trailing Milwaukee by five games, Philadelphia by two and St. Louis by a half-game.

After the victory, the big-screen television in the Houston clubhouse was tuned to the Cubs-Cardinals game, in time to see St. Louis win in the ninth inning. Someone quickly changed the channel to the Reds-Brewers game that was in extra innings.

"We're going to try to win as many games as we can," Berkman said, "and we're certainly going to pay attention to what the teams in front of us are doing."

The Astros have made a habit of finishing strong. In 2004, they went 48-26 in the second half to make the playoffs. In 2005, they went 45-30 after the break and reached their first World Series.

Wolf (10-11) allowed four hits and struck out four in seven innings to improve to 4-1 in nine starts since the Astros acquired him from San Diego on July 22. The Astros have won eight of the nine games Wolf has started for them.

Hunter Pence hit a ball that bounced off the top of the wall in right field for an RBI double in the sixth that prompted the second use ever of instant replay. Umpires looked at the replay and ruled that it was not a home run, upholding the original call.