Real Madrid defender Sergio Ramos has labelled teammate Cristiano Ronaldo as "the best in the world" following the forward's double in their 3-1 win over Barcelona at Camp Nou on Tuesday.

Los Blancos outclassed their arch-rivals in the second leg of their Copa del Rey semi-final Clasico, and the Spain international hailed Ronaldo as the planet's most outstanding player after the game.

"For me, Cristiano is the best in the world, and has always shown up in these types of games," Ramos told reporters after the match.

"We have done very well because against Barcelona it is complicated to find space. The result is deserved."

Jose Mourinho side will meet with Atletico Madrid or Sevilla in the final.