One moment Wednesday, Marvin Williams was playing defense on New Orleans' Robin Lopez. The next, his head was crashing onto the court, raging with pain and spinning.

And, oops, he was going the wrong way.

"It hurt," Williams said Friday before the Jazz's 106-94 loss to the Thunder. "Initially, when I hit it, I tried to get up. Randy (Foye) said he was there, and he told me I started walking the wrong direction. … I was really dizzy for a few minutes."

Williams has gone through a series of NBA-mandated tests since then. He likely won't play again tonight in Houston, and it's unknown when exactly he'll be cleared to resume physical activity.

"I had a bad headache that night," the Jazz's usual starting small forward said. "But it's gotten better, for sure."

Williams still has a "little headache," but he's optimistic his condition is improving. He met with doctors in New Orleans and Oklahoma City, and stayed in bed resting for most of Thursday and Friday.

"(The doctor) just told me to rest up and make sure everything's OK," Williams said. "As long as I have a headache, they told me to take it easy.