Christian Walker singled home the go-ahead run in the ninth inning and the Houston Astros beat the Arizona Diamondbacks 4-3 to complete a three-game sweep.

The Diamondbacks might throw in the towel and accept their fate as a selling ballclub with the trade deadline looming.

The Arizona Diamondbacks, who have intriguing trade options for the Seattle Mariners, fell further out of playoff contention after dropping three straight to Houston.

BOTTOM LINE: The Houston Astros seek to build upon a three-game win streak with a victory over the Arizona Diamondbacks. Arizona has a 50-52 record overall and a 26-27 record at home. The Diamondbacks have the fifth-ranked team batting average in the NL at .253.

The Diamondbacks suffered a tough defeat at home against the Houston Astros, dropping to 5 1/2 games back in the wild-card chase.

Brice Matthews made it three homers in two games at Arizona, erasing a late Diamondbacks lead with a two-run blast.

Framber Valdez pitched seven effective innings for his 10th straight win, Brice Matthews hit his third homer in two games and the Houston Astros rallied to beat the Arizona Diamondbacks 3-1 on Tuesday night.