The boss previewed Monday's match against Girona FC at Montilivi (21:00 CET).
Athletic Club head coach Ernesto Valverde said he is expecting a diffuclt game against a Girona FC side who have "some impressive numbers" so far this season.
Los Leones travel to Catalunya on Monday night, where they will face current the LaLiga leaders at Montilivi (21:00 CET)
"I think it's going to be a tough game. We know there are areas to improve, but we also need to make sure we keeping doing the things we do well," the gaffer said at his pre-match press conference on Sunday evening.
"We must show we're not vulnerable and we want to produce in attack. We know how difficult it will be. It's a big match for us."
Due to the recent international break and Athletic seeing out this weekend's round of fixture, the Lions have not played in 17 days.
Valverde said: "When you're playing regularly and there's a break you always take it with relish it because it feels like you have more time, but as the days go by you just want to compete againt. We're used to it. It depends on how it goes, it can be good or bad for you."
Girona are this season's surprise package, having lost just one of their first 13 matches of the campaign.
"They've been looking good since last year. They were competing to get into Europe until the end. Now they have some impressive numbers," Valverde added.
"They've won 11 games out of 13, only losing against Real Madrid. That's an extraordinary record. They have strengthened well with their signings and they have very good players.
"They're playing well both in attack and defence, they never get nervous and are decisive.
"It's a bit of a surprise, but if they're achieving these things it's because they absolutely deserve to."