Xavier Nady's two-run double in the eighth inning lifted the visiting Arizona Diamondbacks to a come-from-behind 4-2 win over the Houston Astros on Sunday.

It was the sixth consecutive win for the Diamondbacks, who moved into first place in the National League West, one-half game ahead of San Francisco.

Nady, who came to bat after the Astros opted to intentionally walk Chris Young, made them pay for the decision by lacing a two-base hit off Jeff Fulchino (1-3) to the right-field wall, scoring Young and Ryan Roberts. The double extended Nady's hitting streak to seven games.

Juan Miranda added some insurance by driving in Nady on a single to center, and the Diamondbacks held on to complete a three-game sweep.

Diamondbacks manager Kirk Gibson, celebrating his 52nd birthday Sunday, was ejected early after arguing a balk call.

Aaron Heilman (4-0) secured the win with an inning of scoreless relief, while J.J. Putz pitched a spotless ninth inning for his 16th save of the campaign.

Fulchino was tagged for three runs in 2/3 of an inning to take the loss.

Houston starter J.A. Happ helped himself in more than one way, limiting Arizona to a run on two hits over six innings while hitting his first home run of the season in the fifth. Diamondbacks hurler Josh Collmenter was almost as effective, charged with two runs on four hits in his six innings of work.