BOSTON -- When you're in last place at this time of year, all you can really do is look to the future and try to spoil things for contending teams you meet down the stretch.

The Oakland Athletics have been doing just that.

"I think we've been pretty energized since our younger guys have gotten here," Oakland manager Bob Melvin said after his team downed the first-place Boston Red Sox 7-3 on Wednesday night.

The win was the sixth in the last seven games for the A's, who started a five-game winning streak with a victory over the wild card-contending Los Angeles Angels and swept four games from the first-place Houston Astros before splitting a pair of games at Fenway Park.

They are 4-2 this season against the Red Sox, who saw their American League East lead over the winning New York Yankees shrink to three games.

"They've got some power up and down the lineup -- you don't make your pitch they've got a chance to hurt you," Red Sox manager John Farrell said.

Rookie Matt Olson's two-run homer highlighted a four-run first inning and the A's never trailed, scoring six runs off Doug Fister (5-8) in the first three innings as the Red Sox lost for the second time in seven games.

Jed Lowrie had a triple, a double and a single, drove in two runs and scored two against one of his former teams. Olson hit his 18th homer in only 49 games for the A's (64-81).

Rookie Jharel Cotton (8-10) worked the first five innings, allowing three runs and six hits.

"He definitely had to battle through some stuff," Melvin said. "There were a couple of time we were on the verge of getting him out.

"You look at the box score and it doesn't tell you how he battled and had to make some big pitches with the lead."

Cotton, who had been roughed up in his previous two starts, is from St. Thomas, Virgin Islands, and was wearing a T-shirt that read: "VIBVI Strong."

"I put it on this start just because I wanted to get it out there," he said. "I've been doing the fundraising and stuff like that to show that I represent the British and U.S. Virgin Islands."

Five Oakland relievers finished up with a combined four scoreless innings.

Fister came in with a 5-2 record with a 2.79 ERA since replacing injured David Price in the rotation, and was 3-1 with a 1.50 ERA in his past four outings. He failed in his attempt to get his career record back to .500.

Jackie Bradley Jr. homered, Dustin Pedroia stroked three hits and Andrew Benintendi doubled his first two times up for the Red Sox (82-63).

In his past four starts, all lasting at least seven innings, Fister had allowed runs only in the first inning -- and he quickly gave up four Wednesday. But unlike the other four outings, this time he gave up other runs as well.

After the game, Farrell said Fister warms up earlier than other starters and that might have to be adjusted.

In the middle of the fourth inning, a banner was draped over the Green Monster that read: "Racism is as American as Baseball." It was quickly removed and had been brought into the park by five anti-racism protestors who spoke with CSNNE. One of the protestors, speaking on the condition of anonymity, said, "We see Boston continually priding itself as a kind of liberal, not racist city, and are reminded almost constantly that it's actually an extremely segregated city. It has been for a long time."

After the game, Mookie Betts, who drove in the first Boston runs (his seventh RBI in two games), said, "Yeah, I saw it. There's no place for that. That's for another day, though."

The Red Sox issued a statement that read: "During the 4th inning of tonight's game, four fans unfurled a banner over the left field wall in violation of the club's policy prohibiting signs of any kind to be hung or affixed to the ballpark. The individuals involved were escorted out of Fenway Park."

NOTES: The game was delayed 19 minutes by a seventh-inning downpour. ... There were important announcements from both teams -- the Red Sox welcoming David Ortiz back to the organization for a number of roles, including recruiting, and the A's picking a site in Oakland for their proposed new ballpark. ... The Red Sox haven't decided if LHP David Price (left elbow inflammation) will return as a starter or a reliever to help the team down the stretch. Manager John Farrell said, "David and his health. That's what will be the priority." Price threw three innings of a simulated game and said, "I just want to pitch. Whatever it is, that's fine." ... Rookie RHP Daniel Gossett (4-8, 5.02 ERA) goes for Oakland against LHP Drew Pomeranz (15-5, 3.35) in Thursday's matinee series finale.