Rio Ferdinand turns 33 on Monday with Nemanja Vidic offering him a resounding vote of  confidence and warning that it is "wrong" to think his team‑mate will not come through a difficult period in which he has been informed he is no longer an automatic first-choice player at Manchester United, as well as losing his place in the England squad.

Ferdinand looked more like his old self in United's 1-0 defeat of Sunderland on Saturday but these are challenging times for a player whose injury problems have restricted him to only around 40% of the club's games over the past couple of years.

After 81 caps his international career is in danger of fizzling out, with Fabio Capello omitting him from his squad for the forthcoming games against Spain and Sweden. Capello informed Ferdinand during Sir Alex Ferguson's 25th anniversary dinner at Lancashire's cricket ground last Thursday, just a few days after the United manager had spoken publicly about his player "losing the yard of pace he had five years ago" and needing to understand there were younger players coming through.

Vidic, however, believes that Ferdinand has been the subject of some unwarranted criticism since the 6-1 home defeat by Manchester City.

"When you look at what has happened to Rio over the last few weeks, we have to remember this is a player who played in most of the big games last season, helped us win the Premier League title and reach the Champions League final, and yet after one game people are saying he is not good enough any more.

"I think this is wrong and Rio showed that [against Sunderland]. Sometimes when you have been at the top a long time like Rio has, people judge you on your age and they are waiting for one bad game to say: 'Oh, he's finished.' But the way Rio played was the perfect way to show he is not finished. He showed strength of character. He showed he still has the quality and ability to play at the top level. He showed class, he showed determination, as well as his ability to help the players around him."

The Sunderland game was the first time since the opening weekend of the season that Ferdinand and Vidic, once regarded as one of the more formidable centre-half partnerships in the game, had played alongside one another. There was a twist, however. Ferdinand has historically played on the right side of the two but on this occasion Ferguson had asked them to swap sides.

"The manager decided to play me on the right and Rio on the left," Vidic said. "That didn't cause us a problem. Rio had a great game. I think his experience is important, especially when you have young players in the team and the defence is changing all the time. I just hope Rio stays fit because he is a player who can help the young players."