MILWAUKEE (AP) -- Jon Lester's second start was a big improvement over his first outing.
Lester pitched six sharp innings, nailed a runner with his weird, one-hop throw and hit a tricky grounder that was tough to corral as the Chicago Cubs beat the frustrated and fragile Milwaukee Brewers 8-0 Thursday night.
On opening day, he lasted 3 1-3 innings and gave up three earned runs and seven hits at Miami.
"It was better," Lester said. "The rhythm was better. The overall direction of me going toward home plate was better. I was able to execute all my pitches."
The Brewers lost more than a game.
All-Star closer Corey Knebel exited with a hamstring injury while getting some work in the ninth inning. Manager Craig Counsell said Knebel will get an MRI and go on the disabled list.
Knebel clutched his left hamstring as fell to the ground after throwing a pitch to Tommy La Stella, and had to be helped off the field. He had one save this season after compiling 39 last year.
"These guys are putting a lot of torque on their body there," Counsell said. "It's a situation where Corey had been off for six days and we were just trying to get him an inning of work, really, and keep him sharp. To have him go down and a DL stint makes it a rough day, for sure. A loss, you kind of turn the page. But obviously this is a little harder with that."
Milwaukee third baseman Travis Shaw also left early -- an animated argument got him ejected in the sixth.
Shaw verbally disagreed with plate umpire Brian O'Nora's called third strike and walked to the dugout. He turned, said more to O'Nora and was tossed. Shaw then sprinted toward the umpire to have one final say before being restrained.
Jason Heyward homered for the Cubs, who had been shut out in the previous two games.
Milwaukee was blanked for the second straight day after has lost three of four since a 3-0 start.
Lester (1-0) allowed three hits, struck out six and walked one. In the first inning, the left-hander known for having trouble throwing to bases watched Ryan Braun easily steal second. But when Braun tried to take off and steal third, too, Lester went to a bounce toss he's been using this year and threw him out.
The Cubs scored three times in the second off Brent Suter (1-1), starting with a two-run single by Javier Baez.
Lester followed a grounder that glanced off the glove of Suter and went under the mitt of second baseman Hernan Perez, who was charged with an error. The ball kept rolling and trickled in and out of the glove of center fielder Lorenzo Cain, who also was charged with an error that allowing Baez to score from first with a head-first slide.
"When you do stuff like that, when you make mistakes on defense and the other team takes advantage it normally hits you in the solar plexus a bit," Cubs manager Joe Maddon said.
CHANGE IN LINEUP
Maddon inserted Ben Zobrist into the No. 2 spot of the lineup for the first time this season and moved Kris Bryant to third. Zobrist entered the game hitting .364.
"He's been seeing pitches," Maddon said. "He's been hitting the ball hard. Putting him and (Ian) Happ in front of KB and (Anthony) Rizzo, I thought it might help a little bit to feed those two. And then you move everybody else down, which isn't a bad thing. Zobrist has really looked good at the plate so I thought it was wise to get him back up near the top."
Brewers: OF Christian Yelich was not in Milwaukee's lineup with right oblique tightness. He was removed from the game against St. Louis in the seventh inning Wednesday.
Cubs: RHP Kyle Hendricks (0-0) is 4-1 in eight career starts at Milwaukee.
Brewers: RHP Brandon Woodruff (0-0) makes his third appearance and first start of the season.