Manchester United legend Gary Neville can see Sir Alex Ferguson carrying on for another five years.

Former United skipper Neville, who retired last season, paid tribute to Fergie ahead of his former manager's 25th anniversary in charge at Old Trafford this weekend.

"He has now done 25 years in the job and is still here, why should he leave?" said Neville. "He feels as determined as ever and it's a continual challenge to be at United.

"I know that from being a player. I know that from being a fan. That will keep him young. There was a period when people were talking about him retiring, but that has gone away.

"He knows the club, he knows how to make it successful. We have been developing a new side with a lot of young players coming into the squad and hopefully we can continue to bear the fruits of that.

"It wouldn't surprise me if he was to go on for even five more years.

"Whoever eventually takes over will face a daunting task, because there will be so many comparisons - possibly more from outside than from within."