Ferdinand's partnership at the back with Nemanja Vidic was, by popular opinion, one of the main reasons the club won a notable double last season.

The former Leeds and West Ham star is widely tipped to become a future United and England captain.

Ferdinand returned to the side on Tuesday in the victory against Orlando Pirates in the Vodacom Challenge following a back problem.

It was his first pre-season match after he sat out the draw against Kaizer Chiefs at the weekend and the friendly at Aberdeen.

Ferguson said: "Rio has been the best defender in the country if not Europe for a couple of years.

"His maturity and leadership have been key factors in the team's success.

"He is someone that young players learn from and that more experienced players respect.

"I have not seen a better defensive pairing than him and Nemanja for a long time."

United are preparing for the final game of the tournament on Saturday in Pretoria against either the Pirates or the Kaizer Chiefs, who meet on Thursday night.

Then on Sunday they move on to Nigeria for a friendly against Portsmouth before flying home.

After winning the Champions League and retaining their Premier League title, Ferguson feels this is a vital time in their build-up to the new campaign.

He said: "In many ways, having won two trophies last year makes pre-season even more important.

"But I am confident the players have the hunger and the desire to mount a strong challenge to defend their titles."

Ferguson is expected to give another run-out to some of his promising youngsters with Fraizer Campbell, Jonny Evans, Danny Simpson, Chris Eagles, Lee Martin and Darron Gibson all featuring against Pirates.

And according to the Scot, the difference between being on the fringes and being promoted to the team can be down purely to keeping your focus.

He said: "Concentration is one of the vital components of players making that step across the line to be first-team players. We often under-rate the value of concentration.

"They can practice all day long, they can have fantastic ability but if they do not have concentration to make everything happen, then they are never going to be there. That is a fact."