Aramis Ramirez hit a grand slam in the fourth inning as the Chicago Cubs hammered the Houston Astros 8-3 on Saturday night.

Ramirez, who leads the club with 25 home runs on the year, put this one out of reach after the Cubs took a 4-0 lead early on. Center fielder Marlon Byrd also added two hits and three RBIs.

Carlos Zambrano (11-6) held the Astros scoreless until the seventh inning while striking out five and walking three to move to 8-0 since returning to the starting rotation on Aug. 9. He worked 6 1/3 innings and threw 92 pitches before turning the game over to the bullpen following a two-run double to Astros first baseman Brett Wallace.

James Russell, Justin Berg, Scott Maine and Marcos Mateo came out of the bullpen to close it out from there for the Cubs without allowing another hit.

Houston starter J.A. Happ (6-4) hit the showers after giving up seven earned runs over three innings of work. He walked five and struck out three.