Powerful quarter-finals line-up in Champions League

Manchester: Six past winners, three domestic league leaders and many of the world's best players take their places this week in one of the strongest quarter-final lineups in the 22-year history of the Champions League.

There appears to be no weak link in the last eight, with Manchester United unlikely to be written off by quarter-final opponent and reigning champion Bayern Munich despite a disappointing Premier League season in the post-Alex Ferguson era.

Barcelona and Atletico Madrid meet in a matchup between Spain's current top two teams, nine-time European champion Real Madrid aim to avenge last season's semi-final defeat to Borussia Dortmund while Paris Saint-Germain take on Chelsea.

Here is a look ahead to this week's first legs in the Champions League quarter-finals:

MANCHESTER UNITED-BAYERN MUNICH

United come into Tuesday's match on the back of a big win in the Premier League. Bayern head to Old Trafford off a disappointing draw in the Bundesliga.

Don't be fooled, though - that's hardly a representation of their respective seasons.

While Bayern have breezed to the German championship with two months to spare, United have endured a woeful season under David Moyes in the defense of their English title and are languishing in seventh place in the standings.

United, who need to win the Champions League to secure a return to the competition next season, has saved some of their best performances for Europe but will rarely have been a bigger underdog going into a home-and-away matchup.

Bayern have already handsomely beaten Manchester City and Arsenal on trip to England this season and their attacking power should be too much for United's flaky defense.

BARCELONA-ATLETICO MADRID

Despite their contrasting styles, it's tough to have a more evenly matched pairing than Barcelona and Atletico Madrid.

The two sides have already met three times this season and neither have been able to emerge victorious. They drew twice in the season-opening Spanish Super Cup (1-1 at the Vicente Calderon, 0-0 at Camp Nou), with Barcelona claiming the title on away goals, and then again (0-0 at Atletico) in the league.

Tuesday's first leg at Camp Nou will pit the Spanish league leader in Atletico with their nearest chaser as Barcelona trail by one point with seven rounds to go. The two will meet a sixth time this season in the final round of La Liga, which - if neither drop points until then - would decide the title.

Both teams enter on winning streaks and with red-hot strikers - Lionel Messi has scored 36 goals in all competitions for Barca this season and Diego Costa has netted 33 times for Atletico.

The key to the match will likely be whether Diego Simeone's team can again hold Messi and Barcelona's passing attack in check as they so far have this campaign.

"Barcelona, for their history, are perhaps a slight favorite," Barcelona midfielder Xavi Hernandez said, "but if we look at how both teams are playing now, we are on the same level."

REAL MADRID-BORUSSIA DORTMUND

This may not be the same Dortmund side that ousted Madrid from the semi-finals last season, but after appearing invulnerable during a 31-game unbeaten streak, Real Madrid have proven to be more than beatable.

Over the past week, Real slumped to their first back-to-back losses in the Spanish league since 2009, with defeats to Barcelona and Sevilla.

Madrid did manage to bounce back with a 5-0 rout of minnow Rayo Vallecano on Saturday, but even that lopsided victory was tarnished by bad vibrations both on the pitch and in the Santiago Bernabeu stands.

With the win clinched, Madrid stars Cristiano Ronaldo and Gareth Bale seemed reluctant to pass the ball, and some fans dared to jeer Ronaldo when he didn't seek open team-mates.

Ancelotti expected the mood to be different for injury-hit Dortmund, who have endured a frustrating season - particularly when measured against the previous three campaigns - and are 23 points behind Bayern in the Bundesliga.

Robert Lewandowski, who scored four goals against Madrid when the sides met in the semi-finals last year, is suspended for Wednesday's game, and Sven Bender, Jakub Blaszczykowski, Ilkay Gundogan, Marcel Schmelzer, and Neven Subotic have injuries.

PARIS SAINT-GERMAIN-CHELSEA

PSG have muscled into Europe's elite thanks to a huge injection of cash from their new Qatari owners, and the French league leaders are likely to be using Chelsea as an example as they seek to win the Champions League for the first time.

Bankrolled by Russian billionaire Roman Abramovich since 2004, Chelsea have emerged over the past decade as one of the continent's leading powers and are looking to qualify for a seventh semi-final in 11 Champions League campaigns.

PSG are in the quarter-finals for the second straight year but haven't reached the semis since 1995.

The French team have won their last nine matches in all competitions and are closing in on the domestic title but Chelsea, who relinquished top spot in the Premier League at the weekend by losing 1-0 at Crystal Palace, have the tactical edge under wily coach Jose Mourinho as well as more experience in these big games.