CHICAGO -- Scott Hairston hit a three-run pinch-hit homer in the seventh inning to help the Washington Nationals beat the Chicago Cubs 11-6 on Wednesday night.
Hairston, who came to the plate with two out in the seventh and the score tied 6-6, launched a long shot to left off Cubs reliever James Russell, driving in Bryce Harper and Jayson Werth with his 11th career pinch-hit homer.
Denard Span added an eighth inning triple to score Kurt Suzuki and came home on Ryan Zimmerman's base hit. Both runs came off Hector Rondon, the fifth Cubs pitcher of the night, after two were out.
The victory was the second straight for the Nationals; the Cubs have now dropped four of their last five and eight of 10.
Tanner Roark (3-0) worked 1 2/3 innings for the win. He allowed two runs on four hits and struck out three.
Russell (1-4) took the loss after giving up three runs on two hits in the seventh inning.
Nationals starter Ross Ohlendorf, activated off the disabled list earlier Wednesday, had no decision in his first appearance since July 31.
The Nationals replied with three runs in the next two innings.
Cubs starter Jake Arrieta loaded the bases with one out in the second, walking two batters and giving up a base hit to another.
Kurt Suzuki singled home Ian Desmond and Adam LaRoche. Ohlendorf then placed a perfect sacrifice bunt in front of home plate, scoring Steve Lombardozzi from third.
Jayson Werth clubbed his 18th home run of the season in the third with none out, driving home Ryan Zimmerman and Bryce Harper for a 6-1 Washington lead.
Arrieta worked through a scoreless fourth before departing in favor of right-handed reliever Carlos Villanueva. He allowed six earned runs on five hits, walked four and struck out five.
The Cubs erupted for five runs in the fifth and chased Ohlendorf.
Rizzo launched his second homer of the night and 20th of the season -- a two-run shot to right that scored Starlin Castro. The homer cleared the park and cut the deficit to 6-3.
Ohlendorf left the game with one out in the fifth and one runner on base. He allowed four earned runs on six hits, walked two and struck out a pair.
Tanner Roark entered and gave up four straight base hits and three more runs as the Cubs cut the Nationals' lead to 6-5.
Donnie Murphy's single scored Junior Lake while Cole Gillespie had a pinch-hint base hit to drive in Nate Schierholtz.
Welington Castillo then tied the game with a sacrifice fly to center, scoring Murphy.
NOTES: The Nationals officially activated Ohlendorf a few hours before Wednesday's game and inserted him right into the lineup. He had a 5.14 ERA in two rehab assignments. ... Washington also optioned LHP Ian Kroll to Triple-A Syracuse on Wednesday. He was 1-1 with a 3.24 ERA in 27 appearances. ... Werth continues to lead the National League in batting average since July 1. He was hitting .403 since the start of July and .458 since August opened coming into Wednesday. ... The Cubs latest lineup tweak was moving Rizzo from the third spot to second in the order. Entering Wednesday he was 0-for-11 in his last three games and 2-for-24 in the current home stand. ... Wednesday's game was the 13th straight in which the Cubs have faced a right-handed starter. They last were up against a left-handed starter on Aug. 7 in Philadelphia. ... 3B Donnie Murphy is the first Cubs since at least 1921 to hit seven home runs in his first 14 games with the team, according to STATS Inc. ... The Cubs send left-hander Travis Wood (7-10, 3.13 ERA) against National's right-hander Stephen Strasburg (6-9, 2.93) in Thursday's series finale.