from exactly that scenario. Bayern midfielder Toni Kroos had a shot blocked in the Real penalty area and the home side seized possession and poured forward.
Ronaldo played Fabio Coentrao in on the left and his low cross evaded the Bayern defence and found Benzema waiting at the far post to tap into an empty net.
Real were also first to threaten in the second period thanks to an error in the Bayern defence and Ronaldo, back after knee and thigh muscle injuries, burst clear on the right of the area and forced a fine diving save from Manuel Neuer with a low shot.
The Portugal captain has a record-equalling 14 goals in the Champions League this season and was clearly hungry to set a new best and Neuer again had to be alert when Ronaldo cracked a low shot towards the corner in the 68th.
Bayern huffed and puffed, with Arjen Robben and Franck Ribery probing down wither flank, but struggled to find a way through the massed ranks of Real defenders.
After the introduction of Thomas Mueller and Goetze they finished strongly and in a frantic finale Goetze might have done better when left unmarked 10 metres out but Casillas was equal to his fierce shot.
In added time, Bayern claimed a penalty after Xabi Alonso dispossessed Mueller when he was about to shoot but referee Howard Webb waved away their furious protests.
“It was a very tough match, intense and difficult,” Real centre back Sergio Ramos said in an interview with Spanish television broadcaster Canal Plus.
“We worked superbly in defence and we knew how to create our chances and I think it is a satisfactory result to take to Munich and try to make it through to the final.”
Bayern winger Robben, a former Real player, said they had been surprised by the home side’s passive approach and had been expecting to be put under a lot more pressure.
“We expected a storm but they waited. That was a bit of a surprise,” he told ZDF.
“We had chances to score. It was a good game and I liked how we played, especially after the two weeks when we were not in top form,” added the Netherlands international.
Bayern had understandably gone off boil since wrapping up the Bundesliga title last month, while Real beat Barca to win the King’s Cup final on April 16 and are still in with a chance of catching La Liga leaders Atletico Madrid.
The winners of the tie will play Atletico or Chelsea, who drew 0-0 at the Calderon in Madrid on Tuesday, in the final in Lisbon on May 24.