McGehee, Weeks homer; Brewers sweep Nationals
Washington leads the majors with 80 errors and the Brewers made sure both Sunday were costly in their fourth straight win.
Milwaukee took a 2-0 lead on Jonathan Lucroy's RBI single and a wild pitch by Detwiler (0-1) after third baseman Willie Harris misplayed a grounder.
In the fourth, shortstop Ian Desmond bobbled Dave Bush's two-out roller and threw it away, allowing Lucroy to score. Weeks chased Detwiler with his two-run homer that made it 5-0.
McGehee's three-run homer in the seventh off Joel Peralta gave the Brewers an 8-3 lead.
Milwaukee (47-53) has won six straight at Miller Park and hasn't been this close to .500 since May 15. The Brewers have been buoyed by their power surge with at least one homer in 14 consecutive games.
Weeks, who was hit in the head by a Collin Balester fastball on Saturday night, remains on pace to become the second hitter in major league history to have a 100 RBI season from the leadoff spot when he drove in his 64th run in the fourth.
It was McGehee's first homer since July 1 and first multi-RBI game since June 22.
Bush (5-8) looked much sharper against Washington than in his last start when he allowed a career-worst 10 runs — five unearned — in a sloppy loss at Pittsburgh. He retired 13 of 14 Nationals at one point, working around an error by Weeks, before running into trouble in the sixth.
Leading 5-0, Bush allowed a sacrifice fly to Josh Willingham and a two-out, run-scoring single to Adam Dunn. After a double by Alberto Gonzalez put runners on second and third, Ivan Rodriguez flied out to the warning track to end the inning. Bush pitched to one batter in the seventh, leaving after Adam Kennedy's single.
Kennedy later scored on Nyjer Morgan's single off Kameron Loe to make it 5-3, but McGehee answered in the bottom of the inning.
Detwiler didn't allow an earned run, but didn't make it out of the fourth in his first start since right hip surgery in February.
In the first inning, he walked two to load the bases after the error by Harris, who was starting there because Ryan Zimmerman got a day off.
Lucroy's single and Detwiler's wild pitch that Rodriguez tried to backhand gave Milwaukee a 2-0 lead. Detwiler settled down, retiring seven in a row before Lucroy's single started the fourth that he never finished.
Notes: The Nationals have a day off on Monday before rookie Stephen Strasburg (5-2, 2.32 ERA) faces Braves ace Tommy Hanson (8-6, 4.12) on Tuesday night to start a six-game homestand. ... Brewers OF Jody Gerut (left heel) will begin his rehab assignment Sunday night for the Brewers' rookie team in Arizona. He's been on the disabled list since May 27. ... Darin Erstad had 100 RBIs in the leadoff spot in 2000 with the Angels.