Athletic will host Atletico at San Mames.
Valverde said, "They'll be in highly motivated because of their competitive nature.
"They're capable of beating anyone, anywhere. It will be a tough match.
"Atletico Madrid have been very ambitious in investing in the team and trying to get great players. Of course, because of what they have invested, they will look to challenge for LaLiga, as they have done in the past - as well as in the Champions League and the other competitions they're taking part in."
Friday's Europa League will see Athletic face Slavia Prague, Viktoria Plzen, AZ Alkmaar and IF Elfsborg in Bilbao, in addition to away clashes with Fenerbahce, Besiktas, AS Roma and Ludogorets.
"Everything is different. We know the format, but we don't have the experience of playing it," Valverde continued.
"We'll see how it goes. We're playing eight different teams, with four tough away matches. It's an attractive competition and we'll see if we can play well and progress.
"There are no easy opponents in this competition, all of them are difficult. We'll have to sweat for every point."