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Pat Sullivan, Associated Press
Houston Astros' Jose Altuve throws to first base for the out on Arizona Diamondbacks' Gerardo Parra in the sixth inning of a baseball game on Sunday, Aug. 19, 2012, in Houston.

HOUSTON — The Arizona Diamondbacks are hoping to grab a playoff spot with a late surge. They know they need to take advantage of the weaker teams left on their schedule to put together that postseason charge.

It sure went according to plan this weekend.

Aaron Hill homered twice and the Diamondbacks beat the Houston Astros 8-1 on Sunday to complete a three-game series sweep.

Arizona is currently third in the NL West, trailing division-leading Los Angeles by 4½ games. The Dodgers open a three-game series against second-place San Francisco on Monday night.

"We'd like to be closer, we're not right now but we're going to push it right until the end," Arizona manager Kirk Gibson said. "I think we've got a good feel for ourselves."

The Diamondbacks finished 4-2 on their six-game road trip. They return home on Monday to begin a 10-game homestand against Miami, San Diego and Cincinnati.

"It was needed," Hill said of the sweep in Houston. "Hopefully it will carry us into the next few series and just keep it rolling. Maybe we'll catch on fire here and get some momentum and obviously catch the guys in front of us."

The Astros dropped their first game under Tony DeFrancesco, who was the manager at Triple-A Oklahoma City before being promoted to the interim job in Houston. The major league-worst Astros (39-83) fired Brad Mills late Saturday night.

Houston general manager Jeff Luhnow said he made the move to "bring in a new environment" to the National League's youngest team. But it was more of the same Sunday as the Astros dropped their fourth in a row and fell to 7-33 in their last 40 games.

Arizona won its ninth straight game against the Astros.

"If we continue playing and having the drive that we have right now, I think we'll be just fine," center fielder Chris Young said. "We just need have to be able to pick each other up and just continue having the right mindset that we can come out here and win."

Hill, who hit a three-run shot in Saturday's 12-4 victory, hurt the Astros again. He led off the five-run fourth with a drive against Armando Galarraga (0-4) and added another solo homer in the eighth. He also doubled.

Hill has been impressive since he was acquired in a trade with Toronto last August. He hit just .225 in 104 games for the Blue Jays last season, then batted .315 in 33 games with Arizona. He is batting .298 with 17 homers and 54 RBIs this year.

"I never was one to really believe in change and all that, but it's great," he said. "I knew I could play, it just wasn't clicking over there. Then I came over here and whether it's a fresh start I can't answer that, but it's been a great experience for me and hopefully there's more to come."

Young hit an RBI single, Ryan Wheeler drew a bases-loaded walk, pitcher Ian Kennedy hit a sacrifice fly and Gerardo Parra doubled home a run in the fourth to chase Galarraga. Young, who is from Houston, was 7 for 14 with a home run, two doubles and five RBIs in the series.

Galarraga remains winless in five starts for the Astros after being tagged for six hits and five runs in 3 2-3 innings.

Kennedy (11-10) yielded one run and five hits in six innings for his first win since Aug. 3. He is 2-0 with a sparkling 0.71 ERA in two career starts against Houston.

NOTES: Jason Kubel returned to the Arizona lineup after missing the previous two games with a sore neck. He went 1 for 5. ... Houston opens a series at St. Louis on Monday and the Diamondbacks host Miami. ... Houston hitting coach Mike Barnett and first base coach Bobby Meacham were let go along with Mills on Saturday night. Dan Radison took over in the interim as first base coach and Ty Van Burkleo is the hitting coach.