The Braves are trying to use a visit from Oakland, who came to Atlanta with the majors' best record, to prove they shouldn't be dismissed in the NL playoff hunt.
Chris Johnson drove in two runs with three hits, Julio Teheran threw six strong innings and the Braves edged the suddenly struggling Athletics 4-3 on Saturday night.
"We're not giving up. We're not going to crumble," Johnson said after the Braves remained six games behind Washington in the NL East. Atlanta began the night two games behind the NL wild-card leaders.
The A's matched their worst skid of the season by losing four in a row as they fell percentage points behind the Los Angeles Angels in the AL West. It is the first time since April 28 they have not held sole possession of first place in the division.
"It's tough to go through this as a team, but I feel like everyone goes through it and maybe this is our time right now," said Sonny Gray, who gave up four runs in 5 1/3 innings.
"We've just got to go out there and play with confidence."
Oakland has dropped six of seven overall.
"They're a tough ballclub," Johnson said. "They've played really well all year. We're just trying to prove to ourselves we can play with them and we can stay in this thing."
Teheran (11-9) gave up two runs on four hits and three walks. The Braves had lost 12 of 15 before winning the first two games of the series.
Craig Kimbrel got his 36th save in 40 chances.
Manager Bob Melvin said Gray (12-7) had no breaks as he gave up eight hits and absorbed his fourth straight defeat.
"I thought he pitched well," Melvin said. "He got a little tired at the end but three of those hits are bloops; two of them scored runs."
There was a brief delay in the bottom of the sixth when a nude man ran onto the field. He was quickly tackled by security officers and taken off the field.
Stephen Vogt hit a two-run homer and John Jaso also homered for Oakland. The A's also lost four straight from May 22-25.
Atlanta closed it out after Josh Reddick led off the A's ninth with a long flyball that Justin Upton caught at the left-field wall.
Freddie Freeman hit an RBI double and scored on Johnson's single to give Atlanta a 2-0 lead in the first. Upton led off the fourth with a single and scored on Andrelton Simmons' two-out, bloop single to left field for a 3-0 lead.
Upton walked to lead off Atlanta's sixth and scored from first on Johnson's third hit, a hit-and-run single to left-center.
Jaso's homer off Jordan Walden in the eighth cut the lead to one run.
Atlanta celebrated the 100th anniversary of the 1914 Boston Braves. The Braves and A's wore retro uniforms. The "Miracle Braves" spent much of the season in last place before rallying to earn a spot in the World Series, where they swept Connie Mack's Philadelphia A's. Oakland players all wore high socks with horizontal stripes while Braves players stayed with the 2014 style of wearing their pants over their socks.
Vogt is 11 for 30 (.367) with three homers and eight RBI in his last eight games as he has recovered from a 0-for-21 stretch from July 20 to Aug. 6.
Athletics: SS Jed Lowrie, placed on the 15-day disabled list on Thursday with a broken right index finger, has remained with the team and has even fielded grounders. Melvin said Lowrie is trying to keep himself "as close to game-ready as he can without overtaxing the finger."
Braves: Simmons, who did not play on Friday night when he had a headache after having two teeth extracted, was back in the lineup. Phil Gosselin, who hit his first homer on Friday night while filling in for Simmons, started at second base and had two hits. ... RHP Shae Simmons (strained right shoulder) began a rehab assignment with Triple-A Gwinnett.
Athletics: Jon Lester, who beat the Braves on May 27 while with the Red Sox, will look for his fourth straight win with Oakland. He has won seven decisions in a row overall.
Braves: Mike Minor, who is 1-3 with a 7.17 ERA in four starts since the All-Star break, will try to build on encouraging results in his last start, when he allowed three runs in 6 2/3 innings against the Dodgers. Minor has allowed a .372 batting average in those four starts.