Ferguson concerned about Hargreaves' career © EuroFootball.com

Long-time coach Sir Alex Ferguson is seriously concerned about the career of team defender Owen Hargreaves, who just can't seem to get out of the injury crisis.

The 29-year-old footballer started a match for the first time after a two-year break, but he felt pain after just five minutes and had to leave the field.

Hargreaves, who has undergone surgery on both knees, went to the German city of Munich for further tests on his Achilles tendon injury.

"We are all worried," said Ferguson. "He hasn't played for more than two years, so we have to be unrepentant optimists if we think Owen's comebacks will be rosy."

"What we are trying to do is help the guy. It's a huge challenge. We want to get him back on his feet and return him to a level where he can still play football."

The experienced strategist is convinced that Hargreaves was ready to step onto the field.

"An Achilles tendon injury is like a riddle," Ferguson continued. "He looked great in training and there were no concerns about allowing Owen on the field. Unfortunately, our confidence turned against us."