It was Cain's second home run of the year and it helped him improve to 2-3. He struck out four, walked five and gave up seven hits as the Giants won for the third time in four games.

Brian Wilson recorded his National League-leading 12th save.

Omar Vizquel and Randy Winn each doubled and scored a run for the Giants, while Fred Lewis had a three-hit night.

The Astros, who had won four straight, got their runs from Carlos Lee, who homered and drove in a run.

Brandon Backe (2-5) was the loser, allowing four runs -- three earned -- on seven hits over six innings.