The two giants are familiar foes and they meet for the 23rd time -- a record in European competition.
The two giants are familiar foes and they meet for the 23rd time -- a record in European competition -- at the Allianz Arena on Wednesday in the first leg of a heavyweight tie.
Madrid traditionally have fared very poorly in visits to Germany and Bayern are unbeaten at home in more than a year, winning their last seven on the bounce before their own fans.
Bayern fans will never forget their crushing 4-0 loss to Ancelotti's Madrid in the 2014 semi-finals, however, the result remaining their heaviest home loss in Europe.
Having masterminded the Spanish side's run to glory that campaign, Ancelotti was brought in to Bayern to take them all the way in a competition in which they suffered three straight semi-final losses under Pep Guardiola.
His opposite number this midweek will be Zinedine Zidane, his former assistant who led Madrid to Champions League glory last season.
"Your experience as a player is only partially useful when you become a manager, because you also have to study, you have to keep up to date and gain your own experiences, and Zidane has done that," Ancelotti said in an interview with UEFA.com.
"He's charismatic and the players really respect him, and that's very important."
The two sides, top of their respective leagues, both come into the game with defensive worries.
Already without Raphael Varane, Madrid saw Pepe suffer two fractured ribs in Saturday's 1-1 derby draw with Atletico Madrid. Meanwhile, centre-back Mats Hummels is out after he injured an ankle in training on Sunday, a day after Bayern crushed Borussia Dortmund 4-1.
After their unforgettable comeback to beat Paris Saint-Germain in the last 16, Barcelona head to Turin for a clash with Italian champions Juventus.
The Catalans, who won the last of their five European Cups with a victory over Juve in the 2015 final, are not in the best shape heading into the tie after a 2-0 loss at Malaga on Saturday seriously damaged their La Liga title hopes.
This is Barcelona's 10th successive appearance in the quarter-finals, a record, but they are without the injured Rafinha and the suspended Sergio Busquets against opponents unbeaten at home since August 2015.
When asked if Barca's latest domestic setback would impact the tie, Juventus coach Massimiliano Allegri was dismissive.
"For me, it's the same Barcelona. When you have players like Messi, Iniesta, (Luis) Suarez, and Neymar, you don't mess up games very often," Allegri told Italian media after seeing his own side beat Chievo 2-0 at the weekend.
Only city rivals Real have eliminated Diego Simeone's Atletico Madrid from the Champions League in the last three campaigns, so last year's runners-up are unlikely to fear a showdown with Leicester City.
The English champions have undergone a revival since Claudio Ranieri -- who had an unhappy stint as coach at the Vicente Calderon in 1999/2000 -- was replaced by Craig Shakespeare in February.
The Foxes beat Sevilla in the last 16 and had won six games on the bounce before losing 4-2 at Everton in the Premier League on Sunday.
"They won the English league and now they are a different side to when the draw was made. It will be a difficult game, tough, against a team who are similar to us in many respects," warned Simeone.
Top of the French league, Monaco are still gunning for glory on numerous fronts as they go to Dortmund for the first leg of their quarter-final.
The tie brings together two of the most exciting attacking outfits on the continent, and Monaco were boosted by the return to their starting line-up of top scorer Radamel Falcao at the weekend -- his goal secured a 1-0 win at Angers.
Thomas Tuchel's Dortmund will look to Pierre-Emerick Aubameyang for inspiration up front, and it will be a special occasion for the forward against one of his old clubs.
Aubameyang played for Monaco on loan from AC Milan in the first half of the 2010/11 season, scoring twice in 19 appearances.