CHICAGO -- Jon Lester said he appreciated receiving a five-run cushion after one inning Wednesday.

The Chicago Cubs left-hander just wished he had a little better command after his teammates gift-wrapped the big lead en route to a 6-1 victory over the Milwaukee Brewers.

"It seemed like the middle counts got me, (the Brewers) did a good job, too, of fouling some pitches off when we did get two strikes, making me work and having good at-bats," he said. "They really made me grind."

The concerns seemed relatively minor, though. Following the Cubs' first-inning outburst, Lester (13-4) allowed just one run in his 6 2/3-inning outing.

He threw a season-high 118 pitches while limiting the Brewers to three hits and two walks. He struck out seven as the Cubs improved to 6-0 in his last six starts.

"Jon really didn't have his best command tonight," said Cubs manager Joe Maddon. "His stuff was good, but his command wasn't what he normally is. But we did put those runs up early, and we played a nice, clean game otherwise."

The victory was Chicago's third straight in a four-game series that concludes Thursday afternoon.

The Cubs (76-43) have won 17 of their past 20 games, while the Brewers (52-67) have lost five of six.

Chicago roughed up Brewers starter Jimmy Nelson (6-13) with five runs in the first inning and another in the third.

"The first inning, (Nelson) was able to get to two strikes and he just couldn't put away the hitters," Brewers manager Craig Counsell said. "You've got to give them some credit for fouling off some pitches and getting back into counts. I thought his execution certainly went down with two strikes."

Nelson lasted five innings, allowing six runs on six hits. He struck out four, walked two and hit two batters. He has lost six straight and is 1-10 since June 4. Even so, Nelson sees improvement.

"It's going to fall into place, things are going to get back on track," he said. "I feel like I've actually been making more quality pitches, maybe just as much if not more than I was the first couple of months of the season when I was throwing really well."

The Brewers got on the board in the sixth inning when Orlando Arcia drove in Keon Broxton on a fielder's choice grounder. Broxton reached on a single and stole two bases.

The big blow in the five-run first was Jorge Soler's ninth home run of the year. The three-run shot to left with one out off Nelson brought in Ben Zobrist and Addison Russell.

Earlier in the inning, Zobrist singled home Dexter Fowler, while Russell's looping base hit to right plated Kris Bryant.

Lester faced bases loaded with two outs in the second inning but escaped as Nelson grounded to short for an inning-ending fielder's choice.

"You get five runs after the bottom of the first but it kind of relaxes you and then I proceed to get the bases loaded and then (have to) grind," Lester said.

David Ross made it 6-0 in the third with a two-out homer to the back row of the left field bleachers. The solo shot was his eighth of the year.

NOTES: Milwaukee optioned 1B/OF Andy Wilkins to Triple-A Colorado. He was batting .125 in 26 games. ... The Brewers retained RHP Tyler Cravy, the 26th man for Tuesday's doubleheader. He worked two scoreless innings in Tuesday's first game. ... After Thursday's series finale the Brewers are bound for Seattle for a three-game weekend series. ... Milwaukee sends RHP Zach Davies (9-5, 3.80 ERA) against Cubs RHP Jake Arrieta (14-5, 2.55 ERA) on Thursday. ... The Cubs made several roster moves on Wednesday, placing RHP Joe Smith (left hamstring strain)on the 15-day disabled list, recalling RHP Spencer Patton from Triple-A Iowa and putting OF Chris Coghlan (right rib contusion) on the 15-day DL. ... With two-thirds of the season complete, the Cubs are on track for a 103-victory season. ... Chicago opens a three-city road trip with nine games in 10 days starting with Friday's series opener at Colorado.