Kurt Suzuki added two hits and two RBIs and Ryan Zimmerman and Adam LaRoche each had a pair of hits for the Nationals, who remained 15 games behind Atlanta in the National League East and 9 1/2 back of Cincinnati for the second NL wild card.

Tanner Roark (3-0) picked up the win despite allowing two runs on four hits in 1 2/3 innings. James Russell (1-4) was tagged with the loss after allowing Hairston's homer.

Anthony Rizzo hit a pair of home runs for the Cubs, who have lost eight of their last 10. Junior Lake and Nate Schierholtz each added two hits for Chicago, which erased a 6-1 deficit before the bullpen let it get away in the seventh and eighth.

Jake Arrieta, who had allowed only one run in 13 innings in his first two starts for the Cubs, was knocked out after four frames, allowing six runs on five hits and walking four. Washington's Ross Ohlendorf didn't fare much better, giving up four runs on six hits in 4 1/3 innings.

GAME NOTEBOOK: Ohlendorf's RBI on a squeeze play in the second inning was his first since Sept. 27, 2011, for Pittsburgh. … Washington improved to 56-15 when scoring three or more runs. … After hitting in the No. 8 spot for the first time since 2010 a night earlier, Cubs SS Starlin Castro batted leadoff and went 1-for-5. Castro has two hits in his last 32 at-bats.