Although there have been odd blips since his £29.1million move from Leeds in 2002, Ferdinand has largely maintained the form that has seen him viewed as one of the world's best defenders.

Yet, over the last few months, Ferdinand has struggled.

He found it impossible to cope during the Champions League final, although admittedly he was not alone as Barcelona imposed their authority in Rome.

But those troubles have continued this season. He was the man whose casual flick allowed Martin Petrov to send Craig Bellamy charging through to score City's third equaliser in that incredible Manchester derby last month.

And on Saturday, Ferdinand completely misjudged the bounce of a long punt forward to gift Ukraine an opportunity that eventually resulted in Robert Green's dismissal from the World Cup qualifier.

Ferguson has conceded it is the first time he can remember Ferdinand going through such extended torment.

"He has not had spells like this since he joined the club," reflected Ferguson.

"It is an unusual experience for him but he will get through it I am sure of that."

Ferguson has claimed Ferdinand is now clear of the back injury sustained during last season's Club World Cup in Japan.

The problem did rule him out for six weeks though and is said to be at the bottom of the muscular issues Ferdinand has encountered since.

The injuries are an argument the player's manager dismisses completely, although he does acknowledge Ferdinand's frequent absences are a contributory factor in his present travails.

"Games will help Rio," said Ferguson.

"Missing games takes the rhythm away. Getting it back is the challenge now.

"I am sure he has taken the criticism on board.

"I don't know whether it is over-confidence but there has always been a casual part of Rio's game since he was a kid.

"It has been an advantage to him at times. At others, particularly in his younger days, it was a weakness.

"But along with his development and maturity, it has brought about some outstanding form over quite a long time for us."

On the surface, Ferdinand does not appear to be the type of player to be ground down by worry.

Ferguson is not so sure, claiming the Peckham-born star is a deep thinker. And he is sure, to an extent, his form crisis will be preying on his mind.

"All players worry about their form if they are getting criticism," said Ferguson.

"They have to. They wouldn't be human if they didn't.

"We all go through little phases where we have to correct our game or take it a step up. I am sure Rio will do that."