The Tigers took a 2-1 lead in the second when Avila hit a two-run shot off Jeff Niemann (8-5). The All-Star catcher is 25 for 59 (.424) with five homers and 14 RBIs this month.
Niemann, who was 7-0 in his 10 previous starts, allowed four runs and six hits over 7 ⅓ innings.
Jhonny Peralta made it 4-1 in the eighth on a two-out, two-run single off reliever Juan Cruz. The hit came after Jake McGee, who replaced Niemann with the bases loaded and one out, struck out Avila.
Joaquin Benoit and Jose Valverde, who gave up a solo homer in the ninth to Evan Longoria, both pitched one inning to complete a six-hitter.
Brewers 8, Pirates 1; Pirates 9, Brewers 2 - Ryan Doumit homered and drove in two runs as host Pittsburgh ended more than a year of futility against Milwaukee with a win in the second game of a doubleheader.
The Brewers took the opener for their 13th straight victory over Pittsburgh, but the Pirates pounded Milwaukee ace Zack Greinke in the second game.
Greinke (12-5) gave up seven runs and seven hits in 6 ⅓ innings in losing for the first time in a month. The defeat was just the fourth in the last 23 games for the NL Central-leading Brewers, who lost to the Pirates for the first time since July 21, 2010.
In the opener, lefthander Chris Narveson came off the disabled list and pitched shutout ball into the sixth inning. He also knocked in two runs.
Narveson gave up five hits, walked one and struck out three before being forced to leave with one out in the sixth after the nail on his left middle finger started to tear.
Nationals 4, Diamondbacks 1 - Jayson Werth hit a three-run homer, Ross Detwiler took a four-hitter into the seventh inning, and host Washington shut down Arizona to extend the Diamondbacks’ losing streak to a season-high six games.
Henry Blanco homered for the Diamondbacks, who have scored only seven runs in their last six games. Mired in its longest skid since a seven-game run in July 2010, Arizona now leads second-place San Francisco by just one game in the NL West.
