WASHINGTON --- A mammoth milestone home run by Adam Dunn was upstaged by his simple single that helped Washington rally to beat Atlanta.

Atlanta's Tommy Hanson extended his scoreless innings streak to 26 before Dunn's 300th career homer and the Washington Nationals rallied for four eighth-inning runs and a 5-3 victory over the Braves on Saturday.

"That 300th home run would have been hard to talk about. It would have been a useless home run if we hadn't won the game," said Dunn, whose RBI single off Eric O'Flaherty snapped a 3-all tie.

Hanson departed with a 3-1 lead after seven innings and was in line for his fifth consecutive victory before the Braves bullpen blew up, halting Atlanta's winning streak at a season-high five.

"It was remarkable," said Nationals manager Manny Acta.

Mike Gonzalez (3-1) loaded the bases with one down in the eighth on a pinch-hit single by Ronnie Belliard and a pair of walks before Peter Moylan relieved and yielded a two-run, game-tying single to Ryan Zimmerman.

O'Flaherty replaced Moylan and was greeted by Dunn's decisive single up the middle on the first pitch he threw. Josh Willingham followed with an RBI single to left.

"That's the most frustrating part right now. I could really care less about how I did. Tommy goes out there and does such a great job, and obviously our offense is doing really well," Gonzalez said. "We're playing really good ball. Hopefully this doesn't put a chink in what we're doing right now."

John Lannan (6-5) was the beneficiary of the rally. The left-hander allowed three runs and nine hits in eight innings, ending Washington's losing streak at four.

Hanson, called up from Triple-A Gwinnett on June 7 to make his major league debut, took a no-decision in that game and has yet to lose. He allowed only Nick Johnson's single to center in the first and a second-inning infield hit by Anderson Hernandez over the first six innings.