Daniel Murphy hit two of Washington's five home runs and had five RBIs to lead the Nationals to a 14-4 win over the Cincinnati Reds on Sunday.
Adam Lind and Jose Lobaton added two-run shots and Anthony Rendon had a solo homer, his third home run in two games, to help the Nationals to their third win in the four-game series and fourth straight victory overall.
Earlier in the day, the Nationals bolstered their bullpen as they acquired relievers Ryan Madson and Sean Doolittle from the Oakland Athletics for right-hander Blake Treinen and a pair of prospects.
Left-hander Jesus Luzardo and infielder Sheldon Neuse were sent to Oakland as part of the deal.
The Nationals have hit 10 home runs in the series against the Reds, the sixth time since moving from Montreal in 2005 that they've hit at least 10 home runs in a four-game series. Washington has outscored the Reds 29-11 in the first three games of the series, which ends on Monday afternoon.
Tanner Roark (7-6) allowed three unearned runs in six innings. He walked three and struck out five.
Homer Bailey (2-3) allowed eight runs and hits in four innings for his second poor start of the season against the Nationals.
Bailey, who started the season on the disabled list after surgery for bone spurs, made his season debut against Washington on June 24 and allowed six hits and eight runs in 1 2/3 innings. Bailey's ERA in two starts against Washington is 25.40. It's 4.60 against the other three teams he's faced.
Murphy's 15th homer of the season and first since June 28 gave Washington a 2-0 lead in the first inning. The Nationals made it 4-0 in the second on back-to-back leadoff doubles by Lind and former Red Chris Heisey and Wilmer Difo's bases-loaded groundout.
Murphy's second homer of the game followed back-to-back fifth-inning leadoff walks to Difo and Bryce Harper. Rendon's single knocked Bailey out of the game, and Lind hit his seventh homer of the season off reliever Ariel Hernandez.
Rendon led off the seventh with his 19th homer of the season.