Bayern is seeking its third consecutive semifinal appearance, while United has not been in the last four since 2011.
Here are five things to know about Wednesday`s match:
INJURED AND SUSPENDED
Bayern will be without the suspended Bastian Schweinsteiger, after the midfielder got a late red card in the first match. Midfielder Javi Martinez is also suspended because of three bookings.
Also unavailable for the German side are injured midfielders Thiago Alcantara and Xherdan Shaqiri but defender Dante is in contention after being suspended for the first leg.
For United, left back Patrice Evra is pushing for a recall having been absent for the first leg through suspension while striker Wayne Rooney is fighting to be fit after missing Saturday's 4-0 win at Newcastle in the Premier League with a badly bruised toe.
Rooney was present at training on Tuesday and United will be desperate for him to return as fellow striker Robin van Persie is also sidelined with a knee injury.
Bayern will be without the support of 700 fans, meaning that the stadium will have a capacity of 67,300.
UEFA ordered one of the sections in the ground to be closed after Bayern fans displayed anti-gay and political banners at the home match against Arsenal in the previous round.
Bayern has five titles in the top club competition. United three, one of them won memorably over Bayern. In the 1999 final, United scored twice in injury time to snatch the title from the German side in a 2-1 win in Barcelona.
Bayern coach Pep Guardiola, while he was in charge at Barcelona, twice beat United in the final, in 2009 and 2011.
United has never won in Munich, with Bayern winning two and the other two ending in draws.
Bayern has struggled at home against English opposition, especially this season. It lost to Manchester City 3-2 in the group stage and that ended a competition-record 10-match winning streak in the Champions League.
Bayern also drew 1-1 with Arsenal at home in the round of 16, after winning 2-0 in London. Bayern also lost 2-0 at home to Arsenal in the previous season`s round of 16 but advanced to the next round on aggregate.
They also lost the 2011 final at home to Chelsea on penalties.
The first leg may have finished all square but possession-wise, it was all Bayern. With United manager David Moyes content to sit back and rely on the counter-attack, the German visitors enjoyed 74 percent possession and dominated territory.
Still, United had more shots on target than Bayern - 4 to 3 - and Moyes is likely to adopt the same tactics at the Allianz Arena in its bid to pull off either a high-scoring draw or a victory that will send his team through.
It will likely require another huge game from center-back partners Nemanja Vidic and Rio Ferdinand, who produced one of their best performances of the season last week at Old Trafford.
''We can take a lot of confidence from the first leg against Bayern,'' United winger Ashley Young said. ''We have to make sure we take our chances and hopefully we can defend exactly as we did in the first leg.''