The Serbia defender, 30, ruptured three ligaments in his right knee after falling awkwardly following a tussle with Basel striker Marco Streller in United's 2-1 Champions League loss on December 7.

Vidic has been ruled out for the season and faces a year on the sidelines, causing speculation he may never return to his best.

But agent Silvana Martina was remaining optimistic and said her client would return to his best.

"The first forecasts say it can last for a year, but it is meaningless to talk about the end of his career," Martina said on Thursday.

"It's a serious injury but club doctors assure us that the recovery will run smoothly and he will be back on the field."

"It will take time to get back into the old rhythm, but there is no doubt that Vidic will be his old self again. Nemanja is feeling good. He will be back next year stronger and better."