As the ultimate tactician, Pep Guardiola tries to push the boundaries, and we saw an incredibly fluid set-up from Manchester City.
Gabriel Jesus began at left wing-back, then became the central forward. Kevin De Bruyne and Bernardo Silva both acted as false No 9s.
To their credit, City stifled Real Madrid in the first half, and though Isco found a way through on the hour, Jesus hit back and De Bruyne's penalty for a foul on sub Raheem Sterling secured a famous win.
Guardiola is not averse to springing surprise tactical changes in this competition.
As Bayern Munich coach in May 2015, he fielded a back three and tried to go man-for-man with Barcelona's Lionel Messi, Luis Suarez and Neymar. Bayern wound up losing that first leg 3-0.
Maybe it is because of what has happened to Guardiola in the Champions League before that made him want to make these changes.
City were left with a lot to do in second legs in recent seasons — losing 3-0 at Liverpool and 1-0 at Tottenham in first legs. Guardiola didn't want that to happen here and got his way.
