After two seasons lagging behind Chelsea, Alex Ferguson's Manchester United is regenerated and challenging for top trophies again.

A year ago, United was dumped out of the Champions League in the group stage by Benfica and struggling to keep up domestically with the Blues.

``Sometimes you need that disappointment to improve and the young lads that are in the squad have learned from it last season and (it has) driven them on to be even more determined this year,'' veteran winger Ryan Giggs said.

That attitude was evident on Wednesday as United came from a goal down to beat Benfica 3-1 at Old Trafford to reach the final 16 knockout stage of Europe's elite cup competition.

When Nelson's long-range drive on the half hour put the Portuguese side in the lead, the Red Devils were in danger of being eliminated. But Nemanja Vidic equalized with a header just before halftime and Giggs and Louis Saha scored on headers in the second half, putting United through as winners of Group F.

``When we play in that cut-throat way we are a good team,'' Ferguson said after coaching United for the 200th time in Europe. ``Once we get into a rhythm we are a good team and winning the right way is always important at this club.''

United left qualification to the final game after slumping to defeats at Copenhagen and Glasgow Celtic following three straight wins.

But Cristiano Ronaldo relished exacting revenge on his compatriots _ tormenting Benfica with a succession of runs that stifled any hopes of a comeback.

``Last year was bad, but now we've passed into the second round we have a great opportunity to win the Champions League,'' Ronaldo said.

Captain Gary Neville said United is exciting to watch again, but was more circumspect in his assessment of the team's prospects.

``We are still learning but you're seeing more of a maturity in the team and we're killing teams off when we need to. But the result was nothing special, it's what should be expected of this team,'' the England defender said.

``We haven't performed for the last two years, but now we've got another opportunity and we're desperate to do well. No one is going to turn round and say we'll win the European Cup, but we will challenge for it.''

Ferguson is desperate for another Champions League trophy to add to the 1999 title the Red Devils won along with the Premier League championship and FA Cup that year.

The team is also chasing its first Premier League title since 2003, hoping to stop Chelsea from repeating United's feat of winning three straight championships from 1999 to 2001.

With a break of almost three months before the resumption of Champions League action, United can focus on maintaining its domestic lead.

United faces local rival Manchester City on Saturday. Chelsea hosts Arsenal on Sunday.

``It's important for the fans that we finish this week on a high by winning the derby game and carrying on this great run we're in the middle of at the moment,'' Giggs said.