Andres Kudacki/Associated Press

Real Madrid midfielder Luka Modric entered Los Blancos' Champions League tie with Paris Saint-Germain as a substitute on Wednesday, shaking off the adductor injury he suffered while playing for Croatia in the Euro 2016 qualifier against Bulgaria on Oct. 10.

At his peak, Modric has the potential to play a key role for Los Blancos and function alongside Toni Kroos as one of the most threatening midfield partnerships in Europe.

Mateo Kovacic—bought from Inter Milan in the summer—has a similar style, while Casemiro offers power and extra defensive qualities, but neither can dictate the game like Modric.