Atletico Madrid boss Diego Simeone has admitted that his side will have to be at their best to overcome Athletic Bilbao in the second leg of the Copa del Rey quarter-finals.

Simeone's side travel to San Mames on Wednesday evening holding a 1-0 lead from the first leg, but Bilbao are unbeaten on their own patch this season.

"They will be looking to start the game with a lot of intensity and then we'll have to respond, because they will be more confident," Simeone told reporters at a press conference.

"The game will be evenly matched and tight. We don't have a formula, as such, for the game; we have a certain playing philosophy and we're not going to change it."

Atletico are the current holders of the Copa del Rey, having beaten Real Madrid in the final last season.