Martinez's go-ahead RBI single keys Astros' 6-3 win over Rockies

Colorado Rockies' Michael Cuddyer singles against the Houston Astros in the fourth inning of a baseball game in Denver, Wednesday, May 29, 2013. (AP Photo/David Zalubowski) (The Associated Press)

Colorado Rockies' Troy Tulowitzki, left, follows the flight of his solo home run as Houston Astros catcher Jason Castro, right, looks on in the fourth inning of a baseball game in Denver, Wednesday, May 29, 2013. (AP Photo/David Zalubowski) (The Associated Press)

J.D. Martinez hit a go-ahead RBI single in the eighth inning, Carlos Pena connected for a home run as part of a three-run ninth, and the Houston Astros rallied against Colorado's bullpen to beat the Rockies 6-3 on Wednesday night.

The Astros overcame 12 strikeouts and Troy Tulowitzki's first multihomer game since 2011 in taking the opener of a two-game set at Coors Field.

Paul Clemens (3-2) pitched 1 2-3 innings of scoreless relief.

Marwin Gonzalez led off the eighth with a single off reliever Edgmer Escalona (1-2). Jose Altuve was intentionally walked and Rex Brothers relieved Escalona. Brothers struck out Jason Castro but Martinez hit a two-out single up the middle, scoring Gonzalez to put the Astros in front by a run.