A second-half brace from Cristiano Ronaldo turned the game around after Arturo Vidal gave Bayern the lead. Javi Martinez's red card proved the turning point.
Bayern Munich 1-2 Real Madrid
(Vidal 25' - Ronaldo 47', 77')
Defender Javi Martinez was sent off as Bayern Munich were beaten 1-2 by Real Madrid in the first leg of their Champions League quarterfinal.
Arturo Vidal gave the German champions the lead with a powerful header but also missed a first-half penalty before a second-half brace from Cristiano Ronaldo turned the game on its head. Bayern now have it all to do in Madrid in the next week's second leg.
The Bundesliga champions were without their top scorer Robert Lewandowski, who had to watch the game from the stands as he continued his recovery from a shoulder injury.
Coach Carlo Ancelotti therefore selected a team without a recognized striker against the club with whom he won this competition in 2014. Arjen Robben, Thiago, Franck Ribéry and Thomas Müller formed a front four. Jerôme Boateng and Javi Martinez lined up in defense in the absence of the injured Mats Hummels.
Joy and despair for Vidal
Bayern had the better of the opening stages, winning a series of corners and forcing Real onto the back foot, but it was the cup holders who came closest to opening the scoring when Karim Benzema's header came back off the bar.
The Bavarians' pressure continued with Gareth Bale blocking a goal-bound volley from Ribery and from the resulting corner - Bayern's sixth in the opening 25 minutes - Vidal powered an unstoppable header past Keylor Navas.
The Bundesliga leaders continued to dominate proceedings but were struggling to create concrete chances - until the evergreen Robben left former teammate Toni Kroos for dead on the right wing and crossed deep. Vidal met the cross at the back post but this time his header flew over the bar, a chance that the absent Lewandowski would surely not have missed.
Vidal had a chance to make amends five minutes later. After Xabi Alonso won the ball high up the pitch, Franck Ribery danced back and forth on the edge of the box before finally shooting. Referee Nicola Rizzoli adjudged the shot to have struck Dani Carvajal's arm and pointed to the spot. Vidal stepped up and fired his penalty with the same venom with which he had headed his goal, only this time the ball flew high over the bar and into the camera phone-wielding crowd in the stands.
Ronaldo equalizes and the pendulum swings
2-0 at halftime and Bayern would have been in dreamland. As it was, they were brought sharply back to earth immediately after the restart. Perhaps still a little too relaxed, Martinez and Boateng left Ronaldo - of all people - completely unmarked in the area.
The four-time Ballon d'Or winner needed no second invitation and volleyed in a crucial away goal, against the run of play.
Real were almost ahead shortly after but Manuel Neuer saved well from Bale's header in an otherwise quiet game for the Welshman, who is enduring a difficult season.
The balance of play was threatening to tip and it took a huge swing in the visitors' direction in three minutes either side of the hour mark. First Martinez saw yellow for a pull on Ronaldo, then again moments later for a trip on the same opponent and was sent off for a second booking. In 15 second-half minutes, Bayern had lost their lead and a man.
Neuer's resilience finally breaks
The 11-times European champions began to turn the screw. Neuer first saved well from Benzema and then outstandingly from Ronaldo - stopping the Portuguese's fierce shot with one hand at point blank range.
Having been so impressive in the first half, Germany's no. 1 was now all that was keeping Bayern in the match, but not for long. Marco Asensio's cross found Ronaldo in space in the box again and this time his volley crept underneath Neuer to silence the Allianz Arena.
The deficit could have been greater but Sergio Ramos' injury-time header was ruled out for offside, leaving Bayern with a glimmer of hope for the second leg.