LOS ANGELES -- After four innings of watching Yasiel Puig, manager Don Mattingly had seen enough.
Mattingly wasn't willing to specify exactly why he pulled Puig for Skip Schumaker, saying only, "I felt I was going to get a better effort out of Skip."
Puig didn't slide into second base to try to break up a double play in the first inning and got upset after striking out in the third, slamming his bat. He is hitting .346.
"I wasn't prepared well for each pitch. It was a good decision," Puig said through a translator about being removed. "He mentioned Skip could come in and do a better job."
Schumaker went 1 for 1 with a walk.
"I wanted to finish the game, but I agreed with the explanation," Puig said. "The meeting went well. We talked about what every player needs to do to prepare for every pitch."
The Dodgers are off Thursday, and Mattingly said Puig would be in the lineup Friday when the San Diego Padres come to town. The manager wouldn't say whether any discipline was involved Wednesday.
"What he did today wasn't acceptable," Dodgers starter Ricky Nolasco said about Puig. "He's young, he's going to have to learn. It's not going to be a distraction. He's going to help this team way more than what he did."
Last week, Puig was held out of the starting lineup for a game in Miami, but Mattingly reiterated that the 22-year-old outfielder was simply given a day off that had already been planned.
Puig's removal overshadowed a second straight dominating performance by Nolasco, who pitched eight innings of three-hit ball.
Nolasco (11-9) struck out a season high-tying 11, walked one and permitted only one runner to reach third base. Acquired in a trade with Florida in early July, the right-hander won his sixth straight start in August.
"I know what's at stake pitching here and the chase we're in now," Nolasco said. "My breaking stuff was pretty good. I just try to keep attacking the zone and put a lot of pressure on them."
Hanley Ramirez and Andre Ethier hit solo homers for the first-place Dodgers, who earned their 21st victory in August to tie the Los Angeles record for most wins in a calendar month. They avoided a second straight series loss by taking two of three from the last-place Cubs.
The Dodgers' 19th shutout of the season leads the majors, and is their most since 1989, when they also had 19.
"It was a battle from the first pitch," said Brian Bogusevic, who was 0 for 3 against Nolasco. "He never got into a pattern with certain pitches and certain counts or situations. You could never really look for anything in particular. He's pitching as well as anybody for them right now."
Edwin Jackson (7-14) gave up four runs -- two earned -- and six hits against his old team. He struck out five and walked two.
"That's a tough lineup, and the pitching staff is doing well, too," Jackson said. "You have to limit the amount of mistakes you make when you're playing against them."
The Cubs have lost nine of 12, and went 2-4 on their West Coast trip. Manager Dale Sveum was ejected in the bottom of the first for arguing a checked swing by Puig with first base umpire Lance Barksdale.
"It wasn't a good call," Sveum said. "Obviously, you don't want to get thrown out on something like that in the first inning. We said our piece, and then he just kept his head in our dugout for 30 seconds, waiting for somebody to say something else. Unfortunately, I did. I just don't think that's right."
Playing their only midweek home day game this season, the Dodgers scored their first two runs on the homers by Ramirez with two outs in the first and Ethier in the fourth. The 88-degree heat and searing sun had fans crowding under the overhangs in the outfield pavilions and upper deck.
The Dodgers extended their lead to 4-0 in the fifth. After a pair of leadoff singles, Nolasco bunted and Jackson threw the ball past third base. One run scored on the error and Skip Schumaker, who replaced Puig in right field, hit an RBI single.
Kenley Jansen struck out three in a hitless ninth for the Dodgers.
Mattingly said slugger Matt Kemp would play a rehab game at Class A Rancho Cucamonga on Thursday, possibly as the DH. Kemp has been on the DL since July 24 with a sprained left ankle. ... The Dodgers' franchise record for wins in a calendar month is 25, set by Brooklyn in July 1947. ... Chicago fell to 9-17 in Jackson's 26 starts. ... After giving up just 11 homers in his previous 144 innings, Jackson allowed two in his first four innings against the Dodgers. ... The Cubs concluded their schedule against NL West teams with their final road game outside their division. They will travel exclusively within the NL Central in September for the first time since 1997. ... The Cubs return to Wrigley Field on Friday having lost 16 of their last 19 games at home.