Holders Inter Milan stared defeat in the face while Manchester United flirted with danger before both teams were able to sigh with relief after reaching the last eight of the Champions League on Tuesday.

Inter staged an unlikely comeback after being outplayed for long periods to win 3-2 in the second leg of their last-16 match at Bayern Munich to go through on away goals after the tie finished 3-3 on aggregate following a night full of excitement.

United held on after a late goal by Olympique Marseille to beat the French champions 2-1 in a tense affair at Old Trafford for their 100th Champions League success and advance by that scoreline after a goalless draw in France three weeks ago.

The Champions League often produces dramatic endings to closely fought ties but few teams will come closer to defeat before escaping than Inter in Germany, breaking Bayern's hearts again nine months after beating them in last season's final.

Having squared the tie at 1-1 through an early Samuel Eto'o strike, which went through the legs of goalkeeper Thomas Kraft, Inter were soon trailing on aggregate again.

In a superb end-to-end match, Bayern stormed back to lead 2-1 on the night and 3-1 overall with goals by Mario Gomez, following a goalkeeping blunder at the other end from Julio Cesar after 21 minutes, and Thomas Mueller 10 minutes later.

But while Bayern squandered several chances to seal victory, Inter showed the class of champions as Wesley Sneijder gave them cause for hope with a 63rd minute goal from the edge of the box.

Both teams still had opportunities to score again but, with time running out, it looked as though Bayern had done enough to qualify before Goran Pandev struck with a superb left-foot shot after 88 minutes to put the champions into the last eight.

The Italians also became only the second side to advance after losing the first leg at home in the Champions League, a feat last achieved by Ajax Amsterdam -- when coached by current Bayern boss Louis van Gaal -- in 1995-96.

Manchester United were relieved to hear the final whistle, despite looking fairly comfortable following Javier Hernandez's opening goal after five minutes before the Mexican pounced on a Ryan Giggs cross for the clincher 15 minutes from time.

Marseille did benefit from United's injury, which saw John O'Shea and Rafael da Silva limp off with hamstring injuries.

The enforced changes led to some disarray in the United defence as they failed to handle a corner with eight minutes left and Wes Brown headed an own goal to produce a nervy finale.

"It was nervy in as much as we lost two defenders in the game which upset our balance," Ferguson told Sky Sports. "The problem for us was their height and they were always a threat at set pieces."

United striker Wayne Rooney said his team had deserved to go through.

"We are delighted, it was a difficult game," Rooney said. "We knew they were a big physical team but I think we deserved it in the end."

United, under pressure not to concede following a 0-0 draw in the first leg in Marseille, started strongly and were rewarded when Rooney's pinpoint cross found Hernandez who turned the ball into an empty net.

Missing Vidic and Rio ferdinand, United coped comfortably with Marseille's attack and Rooney and Hernandez enjoyed plenty of possession without creating many clear chances.

Andre-Pierre Gignac and Soulemayne Diawara missed good chances to equalise and the French side worked tirelessly after halftime, pinning the home team back but lacking the craft to threaten Edwin van der Sar's goal.

Substitute Antonio Valencia created the second United goal with a deft through pass to Giggs whose neat cross was gleefully swept home by Hernandez.

Marseille refused to lie down and they were rewarded when Brown headed a corner towards his own goal and Paul Scholes was unable to stop the ball crossing the line.

But United kept their shape well in the closing minutes and remained on course for their fourth European Cup and a treble of trophies this season.