CHICAGO -- The Chicago Cubs are proving to be one difficult assignment for contending teams hoping to improve their playoff position.
Jake Arrieta pitched six solid innings and Chicago beat Milwaukee 7-1 on Tuesday night, handing the Brewers their seventh consecutive loss.
The last-place Cubs will try for a series sweep of the Brewers on Wednesday night. They are 18-14 since Aug. 1, including a sweep of AL East-leading Baltimore and two of three in a series at NL West-leading Los Angeles.
"We're figuring out ways to put all the facets of the game together at the same time," Arrieta said. "That's what really good teams do."
Arrieta (8-5) allowed one run and five hits, struck out four and walked two. He has allowed one or no runs in 13 of his 22 starts this season.
Shortstop Elian Herrera made two errors that helped the Cubs score four runs in the first inning, and Milwaukee stranded a runner in scoring position in five of the nine innings.
Since owning a 2 1/2-game lead in the NL Central on Aug. 19, the Brewers have lost 10 of 12.
"We have to get back to the way we played the majority of the first five months," slugger Ryan Braun said. "Every team has a bad week. It's not an ideal time for it to happen to us. But we have to go out there and continue to compete every day, and it will turn around at some point."
Milwaukee's Yovani Gallardo (8-8) allowed a season-high seven runs and eight hits in five innings.
Braun singled home Scooter Gennett in the third, but the Cubs pulled away again in the fifth. Welington Castillo had an RBI double and Arismendy Alcantara connected for a two-run homer, extending the Cubs' lead to 7-1.
"Everybody chipped away, made some things happen," Cubs manager Rick Renteria said. "We took advantage of their mistakes."
Alcantara, who made his big league debut earlier this season, now has eight home runs through 50 games.
Valbuena got two hits and scored twice. Over his past 17 games, he has hit six homers, driven in 10 runs and scored 12.
Cubs shortstop Starlin Castro sprained his left ankle on an awkward slide home in the first inning, and left the game. Initial tests revealed no fracture for the three-time All-Star.
Brewers: OF Carlos Gomez was diagnosed with a sprained left wrist and will not swing a bat for at least one week, manager Ron Roenicke said. The injury could potentially sideline the two-time All-Star for a few weeks, but Roenicke said Gomez will remain available as a pinch runner and defensive substitute.
Cubs: All-Star 1B Anthony Rizzo was diagnosed with a back strain and will miss an extended period of time. Cubs executive Theo Epstein said the injury could be season-ending.
The Brewers and Cubs finish their three-game set Wednesday night. RHP Kyle Hendricks (5-1, 1.91 ERA) starts for the Cubs, aiming to win his fifth consecutive decision. He will face RHP Matt Garza (7-7, 3.58 ERA), who makes his first start since being put on the 15-day disabled list with strained left oblique on Aug. 5.
Although the Cubs front office did not call 3B Kris Bryant up to the majors when rosters expanded this month, Epstein still had plenty of praise for the prize prospect. "He's as advanced and mature and professional as a prospect we've had," Epstein said, before directing his focus at next season and adding, "If anyone can jump into the big league picture in the middle of the season and not miss a beat, it's Kris Bryant."