Sir Alex Ferguson has admitted a growing concern at Owen Hargreaves' continued absence through injury. The Manchester United boss confirmed Hargreaves has returned to Munich for further treatment on the hamstring injury he suffered against Wolves in November that has consigned him to another lengthy spell on the sidelines. Hargreaves was making his first start for over two years following operations on both knees to cure a serious tendinitis problem and Ferguson has previously admitted he has no idea when the 29-year-old will return. And Ferguson admitted to worries about whether Hargreaves can even return to the field in any capacity, let alone the level that saw him selected as England's best player at the 2006 World Cup. "We are all concerned," said the United chief. "He has not played for over two years so we would have to be super-optimistic to think everything in the garden was rosy about him making comebacks. "What we are trying to do is help the lad. That in itself is our biggest challenge. We want to help the lad try to get back to a level where he can still play football."