AC Milan in 1989/90 still remain the last European champions to successfully retain their title, while no side has yet managed it since the Champions League was first established in place of the old European Cup back in 1992.
Los Blancos booked their place in the last four with a controversial extra-time win over Bayern Munich in the quarter finals earlier this week, and will be hoping to go all the way once more.
Atletico, who have still yet to be crowned European champions, will be hoping to reach a third final in the space of four years. But it means a third Madrid derby in the final is not possible.
The other semi-final will see Monaco take on Juventus.
Spearheaded by sensational teenager Kylian Mbappe, Monaco have wowed Europe with their performances to get this stage of the competition, their first semi-final since 2004.
Juve easily dispatched Barcelona in the quarter finals, hammering their lofty opponents in Turin before putting in an incredible defensive display at Camp Nou to preserve their aggregate lead and complete their revenge after losing heavily in the 2015 final.
Real Madrid vs Atletico Madrid
Monaco vs Juventus
First leg ties will be played on Tuesday 2nd and Wednesday 3rd May, with return legs scheduled for the following week. The side drawn first in each tie will play the first leg at home.
The winner of semi-final 2 (Monaco/Juventus) was also subsequently drawn as the 'home' team for organisational purposes for the final, set for Saturday 3rd June in Cardiff.
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