Jagoba Arrasate was in the stadium to witness Aberdeen’s impressive win against the Dutch side and admitted that his side with have to be careful against the "dangerous" Dons.
Aberdeen face the La Liga side in the Basque country on Thursday after they hammered Daugava Riga and stunned Groningen in the first two qualifying rounds of the tournament.
With the San Sebastien side set to lose star forward Antoine Griezmann to Spanish champions Atletico Madrid this week, Arrasate is determined not to underestimate Aberdeen.
He said: "We must be careful, especially in our home game, because the Scottish side are dangerous away.
"They are strong and powerful and they were very consistent defensively.
"Looking at their results, Aberdeen seem to be better away than on home soil.
"I said after the draw we would have rather played the Dutch team because Aberdeen are physically tougher than them and we have struggled against that style. They will be a hard team to break down."
Source: The Scotsman