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Brewers manager Ron Roenicke thought Yovani Gallardo had his best outing of the season. It still wasn't enough to snap out of a slump.

Bartolo Colon won his fourth straight start and Brandon Moss hit a three-run homer to lead the Oakland Athletics to a 6-1 victory over the Milwaukee Brewers on Wednesday.

Gallardo (4-6) allowed six hits and five earned runs in six innings to lose for the fifth time in his last six starts.

"The first six innings were really good," Roenicke said. "That's why I thought that was his best game. It is a shame he throws a game that good and comes out with five earned runs. It is tough."

Gallardo allowed only three singles in the first six innings. But the A's broke a 1-1 tie with five runs in the seventh to win for the eighth time in their last 11 road games. Gallardo said a leadoff walk to John Jaso was the key.

"That hitter, I just wasn't as aggressive as I was throughout the whole game," Gallardo said. "During that seventh inning, that is something dumb, I guess. I got away from what I was doing and the next thing you know I ended up walking him and getting into trouble."

That's because Yoenis Cespedes and Jed Lowrie then singled to load the bases. Josh Donaldson, who finished with three hits, hit a two-run single to right field that gave Oakland a 3-1 lead, and Gallardo was replaced with Michael Gonzalez.

Gonzalez got Seth Smith to fly out, but Moss smashed the first pitch he saw into the stands for his ninth homer of the season — Oakland's 12,000th — and a 6-1 lead. It was just the third hit for Moss in his last 31 at-bats and also snapped an 0-for-9 skid.

Colon (7-2) gave up one earned run and eight hits in seven innings for Oakland, which has won 16 of its last 19 games. He struck out four and walked two.

"He's been terrific," Oakland manager Bob Melvin said. "I could've potentially let him go out there one more inning, but he pitched nine innings last time and gave us a solid seven this time. He's on a nice roll."

Colon is among more than a dozen players who have been tied to a now-closed Miami anti-aging clinic under investigation by Major League Baseball. The right-hander missed the end of last season when he was suspended 50 games after testing positive for synthetic testosterone.

Colon said he was unaware of the report until a reporter brought it up after the game because "I don't like to see the news." He also declined to comment on a possible suspension.

Milwaukee left fielder Ryan Braun, who has also been linked to the clinic, did not play because of a lingering thumb problem. Roenicke said it had nothing to do with the latest suspension rumors.

"I understand why you want to bring this up, but this isn't an issue here," Roenicke said. "And I know it is your job to do that, but it really isn't an issue. That is why I don't need to address it. Because there is nothing it."

Colon, coming off a five-hit shutout against the White Sox on Friday, wriggled out of two jams.

With the score tied 1-1 in the fifth, Milwaukee had runners on first and third with no outs. But Gallardo was out at home when he tried to score on Jean Segura's ground ball to Donaldson at third. Carlos Gomez then grounded into a double play.

In the sixth, Jonathan Lucroy hit a leadoff single and took second on Logan Schafer's sacrifice bunt. But Colon got Yuniesky Betancourt to fly out and then struck out Juan Francisco.

Colon's streak of 18.1 straight innings without allowing a run came to an end in the first when Gomez's triple to center field scored Segura for a 1-0 lead.

Oakland tied it at 1 in the fifth. Lowrie scored from third when Smith grounded into a double play.

Notes: Oakland's 18-6 record since May 11 is the best in the majors. ... The A's improved to 6-24 in their last 30 games in Milwaukee. ... Milwaukee's Scooter Gennett had his first career hit with a single in the ninth. ... The Brewers placed RHP Marco Estrada (4-4) on the 15-day disabled list with a strained left hamstring. RHP Tyler Thornburg was recalled from Triple-A Nashville to take his place. ... Milwaukee RHP Jim Henderson will begin a rehab assignment with Class-A Beloit on Friday. He's been on the DL since May 25 with a strained right hamstring.