Jake Arrieta became baseball's first 20-game winner of the season with a complete-game effort in a 4-0 victory over the Milwaukee Brewers on Tuesday, despite feeling a little "off".

A Cy Young Award candidate, Arrieta scattered three hits, struck out 11 and walked just one in a complete-game collaboration with catcher Miguel Montero.

Arrieta, 29, is the Cubs' first 20-game winner since Jon Lieber went 20-6 in 2001.

"I didn't feel sharp, I felt off," he said. "Those days where you have a handful of starts where it's a tossup, you're not sure the way it's going to go. But your mindset plays a big deal in what the outcome looks like.

"You try to be mentally tough and grind it out."

The Wrigley Field crowd stood and roared approval as Arrieta (20-6) worked a one-two-three ninth that included two strikeouts.

"It's special, the crowd here appreciates it," Arrieta said.

"They were into it from the first pitch and that's what makes playing this game so much fun, it's playing in front of your home crowd in a city like Chicago."

It was his fifth successive outing of eight or more innings, his fourth complete game of the season and third complete-game shutout.

One was a no-hitter on Aug. 30 at the Dodgers, a 2-0 victory that included 12 strikeouts and just one walk.

"You've got to give him credit," Brewers left fielder Kris Davis said.

"He hits his spots and he's got electric stuff, swing and miss stuff in the zone. You've just got to battle and just hope we string (hits) together, but he's tough."

Arrieta got all the support he needed on third baseman Kris Bryant's third-inning two-run home run.

Bryant went 2-for-3 with three RBIs, including an eighth-inning RBI double to make it 4-0. Kyle Schwarber was 2-for-3 and scored twice.

Bryant gave Arrieta a 2-0 lead in the third inning with a two-out homer to left for his 26th of the season.

Bryant's shot, which broke Billy Williams' rookie Cubs home-run record set in 1961, came on a first pitch with two out and drove in Schwarber.

"I was joking around with (Arrieta) after the game and I told him he always has to outdo me," Bryant said.

"But it's so much fun to play behind Jake. He works quick, throws a lot of strikes and he's one of the best pitchers in baseball."