Both teams started in 4-2-3-1s. Kroos, Robben and Ribery played behind Gomez for Bayern with Gustavo and Schweinsteiger as holding midfielders. Real started with Ozil in the middle, Di Maria on the right and Ronaldo on the left with Coentrao at left back instead of Marcelo.
Real were the better team in the first 15 minutes of the game. Initally they looked to press high on Bayern's midfield and counter attack from there but their main control early on came from pushing Bayern back, giving space to their centre backs and then switching play from deep, notably looking to play Di Maria in early on the left. Kroos came very deep to receive the ball for Bayern which limited their transitions early on.
Mesut Ozil was drifting towards the left from his position and though Gustavo looked to track him, Schweinsteiger and Alaba also had to be aware of his movement there. The German created the opening chance of the game when Bayern lost it trying to move from defence to attack and he found Benzema behind the centre back who forced a good save from Neuer.
Bayern looked threatening in the wide areas though, especially on quick transitions to Robben to go 1v1 with Coentrao or the link up of Ribery and Alaba on the left. Ribery was coming deep to receive the ball to try and move Arbeloa out of position and create space behind for himself or Alaba. On 16 minutes he made a run behind Arbeloa with Pepe coming across to cover and Bayern won a corner from which Ribery got the opening goal.
Real's defending was a big problem for them. With their front four, the attacking threat was always there but defensively they did not work as a unit. The front four weren't really tracking back so they were defending the wide areas with the full backs and holding midfielders shuffling across but with Schweinsteiger and Kroos in the middle, Khedira and Alonso were stretched in their work. Arbeloa and Coentrao were disorganised and Ramos and Pepe often had to cover behind them.
Bayern on the other hand were a far better defensive unit; getting back in their own half and making it compact, with Ribery and Robben tracking back in the wide areas against the full backs. Gustavo and Schweinsteiger came deep and made it compact between the lines and if they were enticed up, both full backs covered inside well.
Mourinho swapped Ozil for Di Maria about 20 minutes in but it didn't really help, other than when Di Maria found space to run directly on the counter attack. And because Bayern were defending well as a team, Real's main threats were from winning free kicks or from long balls behind the defenders for Benzema or Ronaldo in the channels.
Meanwhile Kroos and Gomez linked up a couple of times to get in behind on the counter attack, one of which gave Gomez a chance which was saved by Casillas.
At the start of the second period, Real changed back to their positions they had started with; Ozil moving back into the centre and Di Maria out wide.
The main threats for both teams in the second half was the early switch of play to the flanks for the wide men to go 1v1 with the full back.
However Mourinho's players came out with more of a concentration on counter attacking. Benzema had a sniff on goal when he was played through from a lofted ball and then a couple of minutes later the away side broke with numerical superiority and though Neuer saved Ronaldo's shot, Bayern failed to clear and Ozil scored from a pull back from Ronaldo.
Bayern were circulating the ball and playing at a slower tempo but didn't look as much of a threat in the final third. Gomez wasn't supported as well as he had been in the first half and Kroos was too deep which meant they weren't able to penetrate as well between the lines. Muller came on for Schweinsteiger and played behind Gomez with Kroos moving alongside Gustavo but this wasn't effective in creating space in the final third.
Where they did have space though was with the full backs moving forward on either side where they weren't tracked. Lahm found space to put a couple of crosses in on the right but Gomez was unable to put them away. Bayern also looked a danger on set pieces with Madrid failing to clear on a number of occasions and not pushing out well enough to counter.
However Real were the team with the advantage at 1-1 and they were happy to sit back and wait for the opportunity for quick transitions. Ozil made way for Marcelo, who played on the left wing, with Di Maria in the middle and Ronaldo on the right. Marcelo was coming deep to give himself space to run into while the switch of play was still giving particularly Ronaldo more space. Granero came on for Di Maria and surprisingly played the role Di Maria had been playing, ahead of Alonso and Khedira though he was slightly deeper. With a few minutes to go, Marcelo also swapped with Ronaldo.
However it was surprising how they still didn't work well as a unit and Bayern kept showing a good intent going forward for a winner. Ribery was moving inside, creating space for Alaba, who was causing danger with his runs into space on the left. Again Real's wingers failed to track back on both sides and this proved their downfall. Lahm admittedly shouldn't have been allowed to turn past Coentrao who committed himself but both full backs had been finding space and Madrid often lacked meaningful pressure in closing down in the wide areas and cover for the full back, as shown on the second goal. Again it was the Lahm/Gomez combination, though this time from a cross along the floor, highlighting the importance of wide players getting to the byline, something that isn't done often enough nowadays.
Bayern deserved their victory with a better team performance than Real Madrid who were very 'broken' in their play. The gap between their full backs and wingers was a problem for Mourinho's side but even then they didn't defend the wide areas well enough, lacking pressure on the ball and often allowing Robben to cut inside and link up. An interesting second leg awaits but Real have to work better as a unit if they are to go through to the final.