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

Zack Short and Taylor Trammell started the ninth with bunt singles against Kevin Ginkel (1-4). One out later, Walker, a former Diamondback, hit a grounder up the middle to score Short.

Josh Hader pitched the ninth for his 27th save and the Astros, who have won four in a row took a six-game lead in the AL West.

Arizona trailed 3-1 entering the eighth, but Geraldo Perdomo led off with a double off reliever Bennett Sousa (4-0). Ketel Marte singled to drive in Perdomo, Corbin Carroll doubled to right sending Marte to third. Marte scored the tying run on Josh Naylor’s single.

Brandon Walter had held the Diamondbacks to one run and four hits in seven innings. He walked one and struck out five, throwing just 82 pitches.

Marte hit Walter’s first pitch of the game for a home run, his 20th of the season.

The Astros scored twice in the sixth. Walker led off with a double off Brandon Pfaadt, then advanced to third when Yainer Diaz also doubled. But Walker scored when shortstop Perdomo booted Brice Matthews’ grounder for an error. Diaz scored the go-ahead run on reliever Andrew Saalfrank’s wild pitch.

Houston made it 3-1 when Diaz doubled off Trevor Richards leading off the eighth and scored on Mauricio Dubón’s single.

Perdomo went 4 for 4.

Postgame reaction

Walker joined Space City Home Network after the game and discussed sweeping his former team and much more!

Key moment

Sousa got Arizona’s Randal Grichuk to hit into a double play with the bases loaded to end the eighth.

Key stat

Walter has only walked four batters in 53 2/3 innings this season.

Next

Arizona is off Thursday before beginning a nine-game trip Friday in Pittsburgh. Houston returns home to play the Athletics; the Astros have not announced a Thursday starter.