WASHINGTON -- Ramiro Pena, who entered the game in the ninth as a pinch-hitter, pulled a two-run homer to right in the top of the 10th inning against Washington reliever Craig Stammen as the Atlanta Braves beat the Nationals 6-4 in 10 innings Friday to open the three-game weekend divisional series before an announced crowd of 33,130.
It was the seventh win in a row for the Braves (9-1), who scored two in the ninth to tie game at 4. The Nats (7-3) lost for the first time at home this season after six wins in a row. Dan Uggla walked with one out in the 10th and Pena homered to put the Braves ahead for the first time.
The winning pitcher was Eric O'Flaherty (2-0) while Stammen (2-1) was saddled with the loss. Craig Kimbrel picked up his fifth save for the Braves with a scoreless last of the 10th.
Washington starter Ross Detwiler, a left-hander who allowed just four hits, went seven innings while Atlanta starter Julio Teheran, who spent most of last season at Triple-A Gwinnett, allowed four earned runs in six innings.
Drew Storen gave up a leadoff single by Atlanta's Chris Johnson in the ninth and pinch-hitter Pena reached on a bunt single. Pinch-hitter Blake DeWitt put down a sacrifice bunt to advance both runners to bring up leadoff hitter Andrelton Simmons, who struck out looking at a curve that he thought was too far inside. Heyward then walked to load the bases to bring up Justin Upton, who hit a ground single to Ryan Zimmerman at third as Johnson scored. Pena came around to score when Zimmerman threw the ball to second for a possible force but the ball went into right field for a throwing error as the Braves tied the game at 4. Evan Gattis then hit a grounder to Zimmerman at third, who threw to first for the final out of the inning.
Washington's Tyler Clippard took over in the eighth with the score 4-1 and allowed a walk to Jason Heyward, single by Justin Upton and walk to rookie slugger Gattis to load the bases with two outs.
With Storen quickly warming in the Washington bullpen, Clippard stayed in and walked B.J. Upton on a full-count pitch to force in Heyward and make the score 4-2. The Nationals then brought in reliever Storen to face Dan Uggla, who flied out to Span on the warning track in center for the final out of the eighth.
Atlanta's Johnson broke up the shutout bid by Detwiler with a solo homer to center with two outs in the seventh for his first longball of the season to make it 4-1. Detwiler then retired Gerald Laird on a grounder to first to end the inning.
Teheran was replaced by former Washington pitcher Luis Ayala, acquired in a trade with the Orioles earlier this week, in the last of the seventh. It was the first appearance for veteran Ayala with the Braves.
The Nationals scored two runs in the second to take a 4-0 lead as Denard Span and Jayson Werth had back-to-back RBI singles with one out against Atlanta starter Julio Teheran, 22, making just his sixth career start.
Bryce Harper had hit a two-run homer into the second row above the left field fence in the bottom of the first to give Washington a 2-0 lead.
Span led off the first inning by beating out a chopper to third baseman Chris Johnson that was initially ruled an error but was changed to a hit. The throw by Johnson pulled first baseman Evan Gattis, normally a catcher with little pro experience at first, off the bag and two batters later Harper hit his fifth homer -- and first opposite field shot -- of the season.
Gattis then missed a foul pop off the bat of Harper on a windy night in the fifth for an error. Harper eventually drew a walk with one out and stole second with two outs, but Ian Desmond struck out against Teheran to end the inning.
Detwiler, who did not allow a run in six innings in his first start of the year at Cincinnati, allowed two hits and no runs in his first five innings of work. The only hits he gave up in the first five innings was a one-out opposite single by Jayson Heyward in the first and a single in the fifth by Johnson, who was erased on a double play grounder by Gerald Laird.
The teams began the night with the two of the three best records in the Majors. "It is always fun to play in your division," Span, the Washington center fielder and leadoff hitter, said of the three-game series. "It is safe to say we are two of the top teams in the National League. It will definitely be an early test for us." The Braves entered the game with the best record in the Majors at 8-1 and were off to their best start since 1994, when they were 13-1.
NOTES: The Braves on Thursday placed RHP Cristhian Martinez on the 15-day disabled list with a right shoulder strain. ... Washington third baseman Ryan Zimmerman, batting cleanup, appeared in his 1000th game with the Nationals. "It is pretty amazing," Zimmerman said of his time in the nation's capital. "It has been fun. I wouldn't change a thing or a second" of the tenure. ... Reliever Luis Ayala joined the Braves on Friday after he was traded to Atlanta earlier this week by the Orioles for a minor league pitcher. Ayala spent 2003-08 in the Montreal/Washington system. ... Atlanta entered the series with six wins in a row while Washington won its first six home games.