HOUSTON – Lance Berkman hit a three-run homer and Randy Wolf shut down Pittsburgh after a shaky first inning as the Houston Astros continued their second-half surge with a 9-3 victory over the Pirates on 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.

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.