Happ put Chicago ahead to stay with a two-run shot in the third inning. He also led off the fifth with his sixth homer.
It was Happ’s first multihomer game since Sept. 5 against St. Louis and No. 8 for his big league career. The switch-hitting outfielder is batting .375 (12 for 32) with five homers and 10 RBIs in eight May games.
Joc Pederson had two more hits and drove in a run as Chicago won for the fifth time in seven games. Pederson is batting .417 (20 for 48) in his last 12 games.
Josh Bell and Kyle Schwarber hit back-to-back homers for Washington in the first, but Joe Ross (2-4) lasted just 3 2/3 innings in his second straight loss. The right-hander was charged with four runs, two earned, and five hits.
The Nationals dropped three of four against the Cubs, closing out a 3-4 trip. They begin a nine-game homestand Friday night against Baltimore.
Trevor Williams pitched 4 2/3 innings of five-hit ball before Chicago’s bullpen took over. Justin Steele (2-0) got four outs before departing because of right hamstring tightness. Ryan Tepera and Andrew Chafin each worked an inning, and Craig Kimbrel earned his ninth save in 11 chances.
The Cubs’ bullpen has a scoreless streak of 17 1/3 innings over the team’s last five games. It began the day with a 3.24 ERA for the season, second-best in the NL.
Steele replaced Williams with Josh Harrison aboard after a leadoff double. After issuing a walk to Juan Soto, he struck out Bell swinging to preserve Chicago’s 4-2 lead.
Chafin got some help when second baseman Nico Hoerner robbed Bell of a hit with a diving stop in the eighth.
Nationals: Manager Dave Martinez said OF Victor Robles was available off the bench after he left Wednesday night’s 4-3 win with right ankle soreness. X-rays were negative.
Cubs: OF Jason Heyward was placed on the 10-day injured list with a left hamstring strain. OF Nick Martini was recalled from Triple-A Iowa. … 1B Anthony Rizzo returned to the lineup after he left Tuesday’s 6-3 victory over the Nationals because of tightness in his lower back. … Pederson was checked on by an athletic trainer when he batted in the eighth, but he stayed in the game.
Nationals: Martinez planned to announce his starting pitcher for Friday night’s series opener against Baltimore after the game. RHP Jorge López (1-4, 6.35 ERA) starts for the visiting Orioles.
Cubs: RHP Kyle Hendricks (3-4, 5.27 ERA) starts Friday night in the opener of a three-game series at St. Louis. RHP Carlos Martínez (3-4, 4.35 ERA) takes the mound for the NL Central-leading Cardinals.