Manchester United captain Nemanja Vidic has returned to full training following a knee injury.

The 30-year-old defender had been out of action since December when he damaged his cruciate ligament during a Champions League clash against Swiss club FC Basel.

However, manager Sir Alex Ferguson has revealed that Vidic, who has been joined at training by fellow centre-backs Jonny Evans and Phil Jones, may not be ready for the start of the new season next month.

"It's not 100% that Jonny Evans and Vida will start the season," Ferguson told a press conference in China.

"Jonny will start running today. Vida and Phil Jones started full training today, which is very positive. If I can keep Rio Ferdinand fit, then Vidic and Jones should give us ample cover."

Vidic joined the Red Devils in 2006 from Spartak Moscow.