In Houston, Pittsburgh's Dale Berra led off the ninth with a home run and Lee Mazzilli drove in the winning run with a single.
Trailing, 2-1, entering the ninth, the Pirates tied when Berra led off with his second home run of the season. It came off loser Bob Knepper (0-1), who had allowed only seven hits to that point.
Steve Nicosia singled to center and was forced at second by Lee Lacy. Lacy stole second--his third steal of the night--and scored the game winner on Mazzilli's grounder through the middle.
Rod Scurry (1-0), who relieved in the eighth with two out, was the winner. Pittsburgh is 2-0 this season and Houston 0-3.
The Astros took a 2-1 lead with a two-run third. Singles to center field by Knepper and former Pirate Omar Moreno and a walk by Dickie Thon loaded the bases. Phil Garner singled to drive in Knepper and Moreno.
The Pirates scored a run in the first without hitting the ball out of the infield. Lacy led off with an infield single and stole second and third. After a walk to Bill Madlock, Dave Parker got an infield single off first baseman Ray Knight's glove to score Lacy.