Sir Alex Ferguson is concerned utility man John O'Shea could miss the remainder of Manchester United's push for an unprecedented fourth consecutive Premier League title. O'Shea picked up a dead leg in Republic of Ireland's World Cup play-off defeat by France in November but was only expected to be sidelined for a couple of days. He has not kicked a ball since and Ferguson explained a blood clot had thwarted his hopes of an immediate return. He told the Irish Independent: "He's got a terrible injury at the moment. It's one of those sorts of injuries that are unusual. It's like a dead leg except a dead leg is usually only three or four days. "The problem is that the blood clot became all knotted and when it gets knotted you get calcification so therefore it's a long process to clear that up and he'll probably miss the season now." The Old Trafford boss added: "It's a bad blow for the boy and for the team because he can play anywhere."