Juventus boss Massimiliano Allegri has claimed that Cristiano Ronaldo has produced "something extraordinary" at Real Madrid.

Ronaldo now features as a central forward rather than a winger, while the Portuguese star has turned around his season with 18 goals from 10 matches in all competitions since the start of 2018.

Juventus face Madrid in the Champions League quarter-finals with the first leg taking place in Turin on Tuesday night, and Allegri has admitted that his players must work hard in order to prevent Ronaldo from continuing his form.

At a press conference, Allegri told reporters: "We have to be very good as a unit to stop him.

"I think we need to congratulate Ronaldo because for a player to be 30 or 31 and change his playing style completely is something extraordinary."

The fixture is a repeat of the 2017 final, which Real won by a 4-1 scoreline in Cardiff.