"Browns running back Peyton Hillis will be out at least a couple of weeks after re-injuring his hamstring in practice today, a source said.

An MRI this afternoon revealed that he significantly aggravated the muscle.

It happened early in practice on a run up the middle.

Hillis came up limping on the play, grabbing at his left hamstring.

He fired the ball to the ground, then threw his helmet down in frustration."