ST. LOUIS -- The All-Star break will last a week for Mark McGwire.

The major league's home run leader won't play the last two games before the break and he's skipping Tuesday's All-Star game in Atlanta to rest a sore right knee. McGwire, who has 30 homers and 69 RBIs, left after three innings Thursday because of pain in the knee.

McGwire, batting .303 with a major league-leading 75 walks, will stay in St. Louis for treatment during the break. He hopes to play next Thursday when the NL Central leaders start the second half at Chicago against the White Sox.

"My first concern is to try to do everything I can to get ready for Thursday, even though there's no guarantees I'll be ready for Thursday," McGwire said Saturday before the Cardinals played the San Francisco Giants. "But we've got to do something because we've got to stop what I'm feeling and get it better."

McGwire, 37, has been taking treatment for patella tendinitis since spring training and the knee has worsened the last 6-7 weeks. The knee bothered him only in the field before Thursday, when he said the knee was "on fire" as he ran to first base.

On the second at-bat, he said the knee hurt just taking a pitch.

"All I was thinking about was my knee, instead of seeing the ball," McGwire said.

McGwire was voted in as a starter at first base for the eighth time, and it would have been his 12th appearance overall. He's not as disappointed about missing the game, considering he's 4-for-20 with a pair of singles and two RBIs, as he is about missing the home run derby on Monday.

"I haven't been too successful in the game, so the home run derby is probably the most fun about it," McGwire said. "I'll definitely miss that."

McGwire has undergone an array of treatment for the injury, including acupuncture, but both he and trainer Barry Weinberg reported no improvement on Saturday. McGwire said he's been waking up in the night because of the pain.

"I don't expect to see too much progress in the next couple days," Weinberg said. "You know, it's like watching your beard grow. You can't ask every hour."

What they haven't tried -- until now -- is rest. Asked about the odds of McGwire returning on Thursday, Weinberg said, "Ask me Wednesday."

"We've got a great thing going here and you want to be strong toward the end of the year," McGwire said. "I don't want to be sitting on the sidelines."

Braves manager Bobby Cox replaced McGwire on the All-Star roster with Cardinals shortstop Edgar Renteria, who was batting .274 with 10 homers, 38 RBIs and 50 runs scored. McGwire pumped both fists when he learned a teammate was taking his place.

"That's the positive side about it, for me to step aside and give somebody that's never been there a chance," McGwire said. "That's the thing that's cool."

Renteria actually was chosen for the second time.

He had been disappointed his name wasn't on the list Tuesday when the reserves were named, especially because Cox initially had a roster with three second basemen and only one shortstop -- Cincinnati's Barry Larkin.

"I felt a little bit mad," Renteria said. "Now, I feel happy. I think I have the numbers. I try to play hard every day and I do everything to win the game."