Athletic Bilbao coach Ernesto Valverde admits they face a massive test against Atletico Madrid.
Athletic host Atletico today at San Mames.
Valverde said: "We will try to be at our absolute best and make sure they don't perform well.
"They're a great team and very competitive. We know what Atlético Madrid are like. They are one of the big sides and we have to be on it.
"We're sufficiently motivated for this match as it is, regardless of the circumstances that make it an important and significant day for the club. We hope to help everything go well. It will be a difficult game at San Mames, nonetheless."
The match will mark the end of Athletic's 125th anniversary celebrations this year.
Valverde added: "We have to concentrate on the match. That's our job. The players and I are completely focused on the 90 minutes against Atlético."