PHOENIX -- Dave Bush was not particularly sharp on Monday night. All of a sudden, the same could be said of the Brewers.

Milwaukee still owns Major League Baseball's best record since May 20, but in the nearer term, the club has lost four of five games, including Monday's 6-3 setback to the Diamondbacks at Chase Field in which six of the nine hits off Bush went for extra bases.

D-backs third baseman Mark Reynolds accounted for two of those six extra-base hits against Bush (4-8) -- RBI doubles in the first and fifth innings. Reynolds also hit a solo home run off Brewers reliever Carlos Villanueva in the seventh to finish 3-for-3 with three RBIs.

"I was fighting myself all night," said Bush, who lasted just five innings. "I had to work harder than I should in order to make some of the pitches I needed to make."

Still, the Brewers took a 2-0 lead in the top of the first inning and had chances for more against left-hander Doug Davis (3-3), who walked away with his first win in four career starts against his former team. Arizona answered with two runs in the bottom of the first inning and three more in the fifth to take the opener of a four-game series.

Milwaukee hitters were 1-for-10 with runners in scoring position including eight futile attempts after Prince Fielder's first-inning RBI single. That hit was Fielder's second in 27 at-bats on this road trip.

The Brewers' third run came without a hit. After the D-backs took a 5-2 lead in the fifth inning, Davis loaded the bases when he hit Fielder with a pitch, then walked two batters with two outs. Pinch-hitter Gabe Kapler replaced Bush and right-handed reliever Chad Qualls replaced Davis. Qualls promptly walked Kapler, forcing home a run and cutting the Brewers' deficit to 5-3.

Qualls escaped further damage when he struck out Rickie Weeks on a wicked slider to end the inning.

"He made a heck of a pitch," Brewers manager Ned Yost said.

On the plus side, the Brewers finally scored on a reliever. The run was charged to Davis, but it was the club's first in seven games on the road trip with a reliever in the game. Qualls, Tony Pena and Brandon Lyon, who notched his 17th save, limited the Brewers to two hits over the final 3 1/3 innings.

On the trip, Braves, Twins and Diamondbacks relievers have combined to pitch 21 1/3 innings against the Brewers with 10 hits and no earned runs.

"I make nothing of it," Yost said. "It's a 'couple of days' trend. It's not a trend. If you want to put it on three or four days and call it a trend, go right ahead."

Bush was charged with five runs, four of them earned, and squandered the 2-0 lead he was handed in the top of the first inning right away. In the bottom of the first, Arizona answered with two runs of its own, including one on the first of Reynolds' two doubles.

The teams remained knotted at 2 until the fifth, when the D-backs scored three runs, giving them a 5-2 lead. Two of the runs scored when Conor Jackson dumped an RBI single in front of right fielder Corey Hart, whose strong throw home nearly nailed Augie Ojeda when Ojeda was slow to advance.

"I really thought I had a chance," Hart said.

Instead, the throw bounced past catcher Jason Kendall as Ojeda scored for a 3-2 lead. Bush didn't back up the play, so when the throw got by Kendall, Stephen Drew raced home from third and Jackson took second base.

Bush read it as a single off the bat, so his first instinct was to back up the first baseman for the throw back to the infield. When Bush realized Hart had a play at the plate, he was "stuck in the middle."

The scorer gave the error to Hart, so when Jackson scored on Reynolds' second RBI double of the night, it was an unearned run for Bush.

"I wasn't where I was supposed to be," Bush said, "and it cost me."

Bush was coming off a pair of stellar starts in which he surrendered two runs and six hits in 15 innings. From the first inning on Monday, it was a fight.

"He never got settled in to where he was making consistent pitches," Yost said.

"It was the worst I've felt in a while," said Bush.