Luyendyk withdraws from Indy 500

Luyendyk said he called Dr. Henry Bock, medical services director for Indianapolis Motor Speedway, and told him he felt tired and unclear since a crash Friday during practice. Bock examined Luyendyk and revoked his medical clearance to drive.

"I started noticing that I wasn't very coherent," Luyendyk said. "That's when I got back in touch with Dr. Bock and we decided that it probably wasn't in my best interest to race. I don't think I'm functioning the way I should to drive a race car. I don't feel well. I don't feel sharp. I don't feel like I'm with the program. I don't think it's a good idea to get into the car feeling the way I do.

The Mo Nunn Racing driver crashed last Friday, spinning and hitting the wall tail-first. He was taken to Methodist Hospital and later released, but complained of pain in his lower back. Although he practiced on Saturday and Sunday, Luyendyk elected not to run in Sunday's qualifying session.

"I was like I wasn't even in the car," he said. "I didn't feel a connection with the car. I basically wasn't firing on all eight cylinders. I was nodding off all day Sunday. I slept most of the day. I've been nodding off the last three days. That's a symptom of a slight concussion."

Team boss Mo Nunn is considering a replacement for Luyendyk, and hopes to announce a decision soon.

"Our concern, first and foremost, is with is Arie's health and well-being," said Nunn. "He's just not 100 percent. You can't force these things if your body isn't right."