Real Madrid coach Carlo Ancelotti admits his fullbacks could be key at Barcelona tonight.
Real need to overturn a 1-0 deficit to reach the Copa del Rey final.
Ancelotti said: We have to consider that the left-hand side is well occupied by Vinicius. That's why we don't ask our left-back to get forward quite so much, we prefer him to control his area better. On the right, it depends whether we play with Rodrygo or Valverde.
"If it's Rodrygo, we have more width on the right but if Valverde plays, he likes to come inside and then we ask Carvajal or Lucas Vzquez to get forward more often.
"Energy and intensity are important factors in this type of match. The same goes for managing the game from the back, being able to play out well can give you an advantage in the transitions. They are high-pressure games and the experience possessed by some of the veterans could be vital. It's not down to one thing. If I only considered energy levels I would be left with a single profile of player. It's important, but so are other aspects as well."
