Speaking to the Official Club Website, Town b oss Joe Royle confirmed: "There is no signs of structural damage which is a relief. We thought there might be ligament problems and that could have kept him out for several weeks but the scans have indicated that isn't the case.
"The knee is badly bruised though with some swelling and although it's early to make a judgment, normally you are looking at maybe seven to 10 days for a recovery period.
"I would say at the moment Lewis will be doubtful for next weekend and maybe the Carling Cup game on the following Tuesday. The injury also means we have had to pull Lewis out of the Welsh squad and they have been contacted."