ATLANTA — Light-hitting Justin Maxwell's grand slam off rookie Mike Minor in the second inning powered the last-place Washington Nationals over Atlanta 4-2 Wednesday and sent the Braves to only their second home series loss this season.

John Lannan (8-7) gave up two runs, eight hits and three walks in six innings for the Nationals, who have won eight of 15 meetings with the Braves this season. Joel Peralta, Sean Burnett and Drew Storen combined for two-hit relief, with Storen pitching a 1-2-3 ninth for his fourth save in five chances.

Atlanta, which began the day two games back of NL East-leading Philadelphia, lost two of three to Washington, only the second series in 24 at Turner Field this year the Braves lost (19-2-3). Atlanta split four games against St. Louis during a 3-4 homestand but still has the major leagues' best home record at 52-23.

Maxwell was hitting only .132 (10 for 76) with six RBIs before his drive off Mike Minor (3-1) stayed inside the left-field foul pole and went about 10 rows deep. It was just the third homer of the season for Maxwell and ninth of his big league career — but he has three slams in four career at-bats with the bases loaded.

Mike Morse had a one-out double to center, Wilson Ramos singled and Alberto Gonzalez fell behind 0-1 before taking four straight balls.

Minor's ERA climbed from 5.63 to 5.84 as he gave up four or more runs for the third straight start. He allowed four hits in five innings, and struck out six.

Troy Glaus walked in the fourth, moved to third on a double by Matt Diaz and scored on Melky Cabrera's groundout. Prado's fifth-inning single drove in Omar Infante, who led off with a double.

Atlanta wasted scoring chances in the sixth and seventh innings.

Lannan struck out David Ross with runners on first and second to end the sixth.

In the seventh, pinch-hitter Eric Hinske was credited with a leadoff double when centerfielder Nyjer Morgan lost the ball in the sun. Hinske was stranded at third when Burnett struck out Martin Prado.

NOTES: Atlanta lost two of three to the Phillies from April 20-22. ... Washington manager Jim Riggleman said he isn't sure when Morgan will hear the determination of his appeal of seven- and eight-game suspensions.