The Giants took a 4-0 lead in the first inning after an RBI single from Pablo Sandoval and a three-run homer by Hunter Pence. Houston cut into the lead with an RBI single from Brandon Barnes in the second, and an RBI single from Brett Wallace and a sac fly from Jimmy Paredes in the third.
San Francisco starter Barry Zito pitched just 2.1 innings and gave up three runs and seven hits. It's his shortest start since last April, according to the Giants' Twitter account. He was replaced by George Kontos.
Astros starter Dallas Keuchel has given up three hits and four runs through four innings.