In form Real Madrid travel to Man United seeking win
Prior to the 1-1 draw between the teams three weeks ago, the season had appeared to be ebbing away from the Spanish champions, with Barca having assembled a seemingly unassailable 16-point lead in La Liga.
Madrid's chances of catching their sworn enemies remain slim, but the two victories over Barca in the Copa del Rey and the league have injected belief that Jose Mourinho's side can go to Old Trafford and win.
"It's clear that these victories are great for the confidence of the group, because now we face a difficult match in the Champions League," said centre-back Sergio Ramos.
"After the two Clasicos we are going to Manchester convinced that we can win, although with a lot of respect for the opponent, who are a great team."
Madrid's wins over Barcelona owed much to the break-neck counter-attacking football that saw them romp to last season's Spanish title but which appeared to have deserted them in the current campaign.
Mourinho could even afford the luxury of resting several of his most important players in Saturday's 2-1 win at the Santiago Bernabeu, with Cristiano Ronaldo coming off the bench to turn the game in the hosts' favour.
Furthermore, aside from goalkeeper Iker Casillas, who has a broken hand, Mourinho has a full complement of players to choose from.
United's squad has also been largely spared by injury, although there are doubts over the fitness of Phil Jones.
The England international worked hard to stifle Ronaldo in the first leg but was then struck down by an ankle injury and missed Saturday's routine 4-0 win at home to Norwich City.
That one-sided victory took United 15 points clear at the top of the Premier League, allowing manager Alex Ferguson to turn his thoughts to Tuesday's encounter.
"It will be a fantastic night," he said.
"You are talking about two of the greatest clubs in the world. Emotions will be high and I am sure it will be a tremendous match.
"If we can get a blank against us on Tuesday, we would go through. But I think both teams will score. I just hope we get more than them."
Ferguson, who saw United fall to Barcelona in the Champions League final in both 2009 and 2011, feels victory against Madrid would convince his side they have the ability to bring home the club's fourth European Cup.
"To beat Real Madrid on our own ground would be a great step forward for this particular team," he said.
"It would give us a chance of going all the way in this tournament."
United's fans already seem certain to witness one milestone, with Ryan Giggs poised to make his 1,000th appearance in senior football after being rested at the weekend.
Tuesday's game will also mark the first time that Ronaldo has returned to Old Trafford since he left United to join Madrid in a world-record Â£80 million ($120 million, 92 million euros) transfer in 2009.
"This is his house, so there will be a lot of emotion. I hope he doesn't play well because of that," United left-back Patrice Evra told MUTV.
"But Ronaldo is a winner. He is a big competitor. If he can win against Manchester United, he will do it."
In their previous meetings in the competition's knockout phase, United have prevailed only once over two legs, en route to their maiden title in 1968 when they drew 3-3 in Spain after a 1-0 win at home.
Madrid's two most recent away games against United have both been memorable affairs.
The nine-time European champions won 3-2 in 2000 to secure a place in the semi-finals and went through 6-5 on aggregate despite a 4-3 second-leg loss in Manchester at the same stage of the 2002-03 tournament.
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