"Some centre-halves arrive from abroad and they get found out straight away, but Vida has come in and done particularly well.
"Vidic is adjusting to English football well and quickly," said Rio. "He is eager to learn and learns fast as well. You have to in the Premiership because it is a tough stage to come on to.
"Although he is a bit of an uncompromising centre half and he likes to get physical in a match, he has still found out the hard way what the English league is all about in a few games.
"I think it has helped concentrate my mind as well. I had been partnering Wes, who I know very well. But getting to know someone new alongside you makes you focus even more.
"There is little time to learn each other's strengths and weaknesses so you are doing it almost match-to-match as well as in training. You have to be very aware."
Ferdinand turns his attention to Brown's return to fitness:
"The defence are playing well together but Wes was doing very well beforehand and he'll want to get straight back in.
"It has been difficult for the manager this season because he has never really had a settled back four for more than four or five games.
"We haven't had that up until the last few matches and you've seen the benefit of that. But the competition is going to start hotting up over these last few matches.
"I am comfortable playing with all the guys and no matter the combination the manager wants then I am happy."