Player-boss Dennis Wise may have dreamed of recreating his part in Wimbledon's upset of 1988, but this was instead Chelsea's 1994 mauling by United all over again.

However hard Millwall ran and battled, United were simply a class apart.

Millwall's entire policy was one of containment, with a five-man midfield and Neil Harris virtually isolated up front on his own as he gamely chased lost causes.

United initially let them off the hook as van Nistelrooy placed an early header wide and Roy Keane's volley was superbly tipped over the bar by Andy Marshall.

It was still rather a half-baked affair, with even a streaker keeping his clothes on, and Millwall were restricted to rare counter-attacks, mainly through the lively Paul Ifill.

United first looked to have made the breakthrough just before half-time, only for Darren Ward to hack the ball off the line after Ronaldo's shot had squirmed under Marshall's body.

However, it was only a couple of minutes before they did get the goal which they deserved for their patient siege of the Millwall goal.

When Keane spotted Gary Neville on the overlap, he spread the ball out wide and, having taken one touch, the England full-back crossed invitingly for Ronaldo to stoop and head past Marshall.

If Ronaldo is tipped for stardom, then Darren Fletcher is also highly rated by Ferguson and his dazzling run just after the restart deserved a better finish.

Marshall also produced a smart save to deny Scholes, while Wise, who had been booked for leaving his boot in on Ryan Giggs, managed to clear Mikael Silvestre's header off the line.

However, the match was effectively over with 24 minutes left when former Arsenal trainee David Livermore brought down Giggs in full flight inside the penalty area.

Van Nistelrooy may have missed three of his previous five spot-kicks but this time he made no mistake.

With the game petering out as a contest, Giggs was able to canter through the Millwall defence to cross for van Nistelrooy - seemingly offside - to finish from close range for the third.

'Winning the final and scoring two is fantastic. I missed the last penalty I took but I was convinced I wouldn't miss this one. 'Millwall were well organised and did very well so all credit to them.

'It's the biggest cup in the world so I am very proud.'

Old Trafford skipper Roy Keane added: 'We knew we had a hard game and all credit to Millwall, they were outstanding. 'The goal before half-time was very important for us, they were playing with a lot of confidence as the game went on.

'We were on a hiding to nothing, they were comfortable on the ball and can play a bit.

'But we were hopeful in the end the quality would tell and it did.'

Gary Neville hailed the contribution of teenager Ronaldo, who headed United in front just before half-time.

'The goal before half-time really settled us down,' Neville said. 'It looked simple in the end but it wasn't. 'We had to be very professional, I don't think were outstanding but Ronaldo in particular was brilliant.

'I think he can be a world-class player. He is only 19 and to come with the massive price tag he has done very well for us.'

United manager Sir Alex Ferguson agreed, adding: 'If we look after him the right way he is going to be one of the stars of football.' Ferguson added: 'You have to respect your opponents at all times and the players did that, they never took it for granted.

'It took us half an hour to start opening them up but with professional players you expect a professional performance. 'It's marvellous and I feel proud of everyone attached to the club.'

United goalkeeper Tim Howard said: 'For me it is awesome to win a cup and get a medal in my first year. It is a good feeling, better than advertised.' Millwall player-manager Dennis Wise was upset to lose.

He said: 'My players have done very well but had we not gone in 1-0 down at half-time it might have been different. 'That goal killed us off. We made a mistake and we got punished.

'I told the players we were done by a sloppy goal, the second I don't know if it was a penalty and the third was offside. But it was fantastic for us - we gave it a go.'

Lions striker Neil Harris said: 'We did what we could, had a game plan and stuck to it. It was disappointing to be 1-0 down at half-time.

'We were punished for a mistake for the first goal and even though Ruud van Nistelrooy got two goals he had a quiet game. That tells you everything.'

Millwall assistant boss Ray Wilkins saluted the battling performance of the Londoners.

'The players did themselves and the club proud. We are not too pleased with the scoreline.

'We worked extremely hard and are proud. United are a good side, the pass well. They were a little bit fortunate but the better side won. Our lads have learned a lot.'

As they lifted the trophy, the cup winners wore shirts bearing the name and squad number of tragic United youngster Jimmy Davis, who was killed in a car crash last August.

Reports from Sky Sports: www.soccernet.com