Updated

First-year owner Jim Crane believes firing manager Brad Mills and replacing him with interim manager Tony DeFrancesco will help the hapless Houston Astros win more games.

That plan got off to a slow start Sunday.

Houston dropped its first game under DeFrancesco when Aaron Hill homered twice to lead the Arizona Diamondbacks to an 8-1 win and a series sweep.

DeFrancesco was the manager at Triple-A Oklahoma City before being promoted. The major league-worst Astros (39-83) fired Mills late Saturday night.

"We need fans in the building and we want to win more ballgames," Crane said following Houston's fourth consecutive loss. "We think this is a process that will help us win more ballgames. The team was really struggling and the demeanor in the clubhouse wasn't what you want it to be. If there's a message to the fans, it's that we're going to make good decisions and we want to win."

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 fell to 7-33 in their last 40 games.

DeFrancesco, who has managed in the minors for 17 seasons, said he "almost fell to the floor" when Luhnow offered him the position and that it's something he's been waiting for his entire career.

"My first major league managing game didn't work out the way I wanted it," he said. "But it was an honor to put the Astros uniform on and be part of the organization. I'm excited to get it going."

Arizona won its ninth in a row against the Astros.

The Diamondbacks hope this sweep will give them momentum as they look to make a late-season surge. Arizona is currently third in the NL West, trailing the Dodgers and Giants.

"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."

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.

Chris 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.

"Once you're down early, you feel the vibes from the players," DeFrancesco said. "It's an uphill battle that they've been doing all season. I'm trying to keep these guys motivated for nine innings, every single out."

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

He said Sunday was a bit of a whirlwind for the team.

"There's a lot of changes that happened in a couple hours," Galarraga said. "(DeFrancesco) was a winning manager in Oklahoma City and he brings a lot of energy here."

Kennedy (11-10) yielded one run and five hits in six innings for his first win since Aug. 3.

Crane said he hopes to name a regular manager by Nov. 1, but it could be much sooner and DeFrancesco would be considered for the full-time job.

"We'd like to whittle our list of candidates down to three or four pretty quickly," Crane said. "If there's a guy that comes in and knocks our socks off, it might be in two weeks."

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.