Gallardo strikes out 11 in Brewers win
Prince Fielder hit his 25th homer and Craig Counsell added a homer and three RBIs for the Brewers, who won consecutive games for the first time this month after a miserable 8-16 start to July.
Milwaukee came into the month with a two-game lead in the NL Central and needed to rally behind their promising young right-hander.
Gallardo (10-7) scattered five hits and a walk. He struck out a batter in every inning but one, but allowed a three-run homer to Ryan Zimmerman in the fourth that made it 3-2.
Fielder answered with a solo shot in the bottom of the inning to tie it.
Cameron started the seventh with a double off starter J.D. Martin (0-2) and advanced to third on Casey McGeheeís single.
Jason Kendall followed with a grounder to third and Zimmerman made an accurate throw to the plate, but plate umpire Joe West, working his 4,000th game, said Nieves didnít get the tag down in time to the catcherís disbelief. West earlier tossed Nationals interim manager Jim Riggleman for arguing.
After Cameronís slide, Milwaukee added three more runs. The Brewers scored one more in the seventh when second baseman Anderson Hernandez failed to complete a double play after a poor throw on a grounder by Counsell and two in the eighth on Cameronís sacrifice fly and a wild pitch by Mike MacDougal that scored Corey Hart for the final margin.
Counsellís two-out, two-run homer in the third gave Milwaukee a 2-0 lead. It was his fourth this season after hitting four over his previous two seasons combined.
But Zimmerman, who has four homers in his last seven games, answered in the fourth with a two-out line drive shot to left center after Gallardo allowed a single to Nyjer Morgan and walked Johnson.
Fielder tied it at 3 in the bottom of the fourth and Gallardo struck out Johnson and Adam Dunn in the sixth to strand Morgan at third.
Dunn threw his bat toward the Nationalsí dugout in frustration, part of many this season for the team with the worst record in the majors (32-70).
NOTES: West is the 19th man to work 4,000 games and fifth among active umpires. ... Nationals OF Josh Willingham (neck strain) was a late scratch.