Darwin Barney doubled in the go-ahead run in the top of the ninth as the visiting Chicago Cubs came from eight runs down to edge the Washington Nationals, 10-9, on Thursday.

Carlos Pena belted his 19th homer and Blake DeWitt added a three-run shot for the Cubs, who avoided a sweep of the four-game series.

The Nationals looked like they would run away with it when they struck for seven runs in the third, knocking Matt Garza out after two-plus innings. Five players had RBI hits in the rally, with Wilson Ramos and Danny Espinosa knocking in two apiece.

But Chicago battled all the way back, capping a six-run rally in the sixth with DeWitt’s homer and knotting it at 8-8 in the seventh on Pena’s shot.

The teams traded runs in the eighth and the Cubs finally took the lead for good in the ninth when Tony Campana used his speed to beat out a possible double-play ball and keep the inning alive. Campana stole second and came home easily when Barney drove a double into the right field corner off Henry Rodriguez (3-2).

Sean Marshall (5-2) picked up the win and Carlos Marmol worked out of a jam in the ninth for his 18th save.