The 42-year-old coach is wary of the challenge that his side will face against La Liga's 14th-placed sideAtletico Madrid coach Diego Simeone is preparing his side for what he believes could be "one of our toughest matches in recent times" when they face Athletic Bilbao on Sunday.
The Argentine coach, who had two spells as an Atletico player, said that Bilbao's current Liga position of 14th place is irrelevant to how the side will play.
Simeone was particularly concerned over Bilbao's sensational performance against Real Betis, in which Bielsa's men produced a cultured performance to earn a 2-0 win.
“I do not look at the table. Bilbao's last game against Betis was very good, and this will be one of our toughest matches in recent times," he told reporters.
“They are one of the best teams in the League. They have some great front players like Susaeta, Muniain, Ander Herrera and Aduriz.”
However, the respect is mutual, with Bilbao defender Iraola conceding that his side will have to be at their best to defeat Simeone's side.
“We will have to play a very good game. They are a team that leave very few spaces at the back and can counter-attack well.
“We are going to have to produce a brilliant performance.
“There have been signs of improvement from us in recent weeks, but tomorrow will be a real test for us.”