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LOS ANGELES -- Getting shut out by Clayton Kershaw was the least of the St. Louis Cardinals' problems. They may have to do without first baseman Lance Berkman for a while because of an injured right knee.

Kershaw outdueled Jake Westbrook with a six-hitter for his fourth career shutout, leading the Los Angeles Dodgers to a 6-0 victory on Saturday night.

"The first couple of innings I threw mainly fastballs," said the 24-year-old left-hander, who is 14-1 with a 1.40 ERA in his last 19 starts at home. "Once I established it, I used my breaking ball more, and the combination worked. They have a great lineup, but losing Lance Berkman is a big blow for them."

Berkman injured himself stretching for a throw from shortstop Rafael Furcal on Justin Sellers' groundout for the third out of the second inning. Matt Carpenter took over at first and committed a fielding error on a hard-hit grounder by former Cardinal Adam Kennedy in the fourth, allowing the game's first two runs to score.

The switch-hitting Berkman, a six-time All-Star and the NL comeback player of the year in 2011, has played in only 13 games this season and is batting .333 with a homer and four RBIs.

In Friday night's series opener, he homered as a pinch-hitter against Dodgers closer Kenley Jansen with two out in the ninth to tie the score, before the Cardinals lost in the bottom half on a bases-loaded walk. The homer ended the longest season-opening home run drought of his career after 40 at-bats.

Berkman had just come off the disabled list last Sunday after being sidelined for 21 games because of a strained left calf he aggravated while chasing a popup. Another trip to the DL is a distinct possibility, judging by the way he was limping around in the clubhouse.

"I wish I knew," said Berkman, who has been on the DL five times. "We're just going to wait and see what the MRI says, but it just doesn't feel right. It buckled on me twice, and I don't know why it did that. I was able to move around OK in here, and then it buckled again. So I have to be careful with it. It's not too painful, but it's just a weird feeling. I wish I could describe it. There's a little bit of instability that's mildly concerning."

Kershaw did not walk a batter for the third time this season while lowering his ERA from 2.22 to 1.90.

"It's scary, but he keeps getting better," catcher A.J. Ellis said. "It just gives us a ton of confidence in this clubhouse that when it's his day to pitch, he's going to give us an awesome chance to win the game. You know what you're getting with Kersh. He's the same consistent guy on and off the field, and he knows he's got a job to do no matter what the circumstances. He wants every game real badly, but you could tell he really wanted this one."

The reigning NL Cy Young winner earned the seventh complete game of his career on 116 pitches, striking out four and not allowing a runner past second base against an offense that came in leading the NL in team batting average, runs, homers, on-base percentage and slugging percentage.

Sellers triggered a four-run seventh inning with his first home run of the season for the NL West-leading Dodgers, who improved the best record in the majors to 27-13.

The Dodgers beat the defending World Series champions for the sixth straight time -- their longest winning streak against the Cardinals since an eight-game stretch from July 24, 1975 through May 12, 1976.

Westbrook (4-3) was charged with four runs -- three earned -- and six hits in 6 1/3 innings. The 34-year-old right-hander, pitching at Dodger Stadium for the first time in his 12-year career, departed after giving up Kershaw's opposite-field double off the glove of left fielder Matt Holliday. It was Kershaw's first extra-base hit after hitting 28 singles over five seasons.

Tony Gwynn Jr. greeted Eduardo Sanchez with a single that drove in Kershaw. The Dodgers got two more runs that inning when Gwynn scored on Sanchez's wild pitch and Andre Ethier added an RBI single that increased his NL-best RBI total to 36.

Westbrook knew he would have his work cut out for himself facing the Dodgers' ace, but he didn't let that distract him.

"You try not to do that, because you always want to go out there and throw a decent ballgame and put up zeros no matter who you're facing," Westbrook said. "If you put too much added pressure on yourself, it's really counter-productive. So you just go out there and pitch your game and do the best you can."

Ellis doubled his first two times up, and has reached base with a hit or a walk in 31 of his first 32 games -- including the last 28 in a row. He entered Saturday with a .459 on-base percentage, the second-highest in the majors behind the Mets' David Wright (.510).

Game notes

Dee Gordon, the Dodgers' regular SS and leadoff batter, got the night off after going 2 for 31 with 10 strikeouts and one walk in the previous seven games. Mattingly said before the game that he will sit him for a few days. ... Kershaw, who led the NL with 248 strikeouts last season, has made 13 consecutive starts without reaching double digits in strikeouts. ... In eight starts this season, Westbrook has yielded just one run over the first three innings. He has made only two other regular-season appearances against the Dodgers, both in relief for Cleveland in 2003.