Hardwick was hurt on the seventh play from scrimmage. He limped off the field and later was taken into the locker room on a cart. X-rays were negative, and Hardwick said he'll have an MRI exam Monday.
"I don't really know what's going on in there," said Hardwick, whose foot was stepped on by another player.
He was replaced by Cory Withrow.
"That's a big issue," coach Norv Turner said. "He's an underrated player. I don't know if people understand how good he is. I've been around some real good centers, and he's as good as I've been around."