SEATTLE -- The Seattle Mariners know Alex Rodriguez's head is going to be all right. It's his right knee that concerns them.

	Alex Rodriguez suffered a concussion Friday after a collision at second base with the Dodgers' Alex Cora. A-Rod will not play in the All-Star Game.

In Friday night's game against the Los Angeles Dodgers, Rodriguez suffered a concussion when hit in the head by the knee of Dodgers shortstop Alex Cora as he attempted to break up a double play.

When he fell after the collision, Rodriguez twisted his right knee as well.

The concussion will keep him from playing for a week, meaning he won't start for the AL in Tuesday night's All-Star Game. He accepted the decision by Mariners doctors and was grateful that he wasn't hurt more seriously.

Rodriguez reported to the Mariners trainer's room at Safeco Field on Sunday for treatment of his right knee. There is a chance the meniscus cartilage in his knee could be torn.

"I hope not," said Rodriguez, who missed 32 games early last season with torn meniscus cartilage in his left knee that required arthroscopic surgery. "It doesn't feel like it's torn. It's a little more bit more swollen today, but it feels a lot better."

He said he was encouraged because he rode an exercise bike for 18 minutes Sunday. After his treatment, his right knee was heavily taped and he walked slowly to his locker.

Rodriguez reported that if he does have a cartilage tear, it's on the inside of his right knee, and he would miss only two weeks if he required arthroscopic surgery again. He explained that his torn left knee cartilage last season was on the outside of his knee.

Rodriguez said he might undergo a magnetic resonance imaging test in Atlanta, where he flew to Sunday after undergoing treatment, or in San Diego, where the Mariners open the second half of the season.

Right now, Rodriguez is unable to have an MRI because of the swelling.

However, he doesn't have a hangover from his concussion.

"The irony is I have no headache," he said. "I feel incredible."

Said manager Lou Piniella: "We're fortunate that it's only a one-week thing. But we're a little concerned about his knee. Hopefully, he'll be able to go in San Diego. We'll have to see."

Rodriguez was hospitalized overnight after his concussion. He was released Saturday and came to Safeco Field for treatment. Then he dressed in uniform and joined his teammates on the bench in an 11-0 victory over the Dodgers.

"I guess they don't need me," he said.

Despite not being able to play, he flew to Atlanta for the All-Star game.

"I need to get some sleep," he said. "The nurses kept waking me up in the hospital every two hours asking me what my name was."

Rodriguez, a four-time All-Star, said he planned to be in uniform and sit on the AL bench and cheer for his teammates. He admitted he was sorry he couldn't play.

"It kills me that I can't get an opportunity to play," he said. "You feel you've accomplished something and now you feel cheated."

After the All-Star break, the AL West-leading Mariners play against the Padres beginning Thursday. They'll work out in San Diego on Wednesday.

Despite his injury, Rodriguez said he didn't plan to alter the way he played. He will try to break up double plays even though it means the risk of major injuries.

"I only know one way to play and that's all out," he said. "I went in hard (Friday night) and he (Cora) went in hard."

Rodriguez, who will be 25 on July 27, had a great first half, hitting .345, scoring 84 runs in 84 games and hitting 24 homers with 78 RBI.

With Rodriguez sidelined, Carlos Guillen is the Mariners' starting shortstop.