Tests have shown that Stefan Stam (pictured) has torn cartilage in his knee after Athletic's reserve game on Monday. Stam will now require keyhole surgery and could be out of action for up to six weeks. The Dutchman was in contention for a place in defence for the FA Cup tie at Chasetown on Sunday but this breakdown means that he will now undergo his second knee operation of the season. Guy Branston is struggling with a calf problem, Marc Tierney has a sore leg, Rob Scott has Achilles problems and Danny Hall has a tender knee but all are expected to be fit for the cup clash even though manager Ronnie Moore has hinted that there will be changes in defence.