Bayer are at Anfield tonight for their clash with Xabi's former club.
The Spaniard said, "I think if I have to share with my players what will happen here, I will. But everyone has their own feelings, good memories but also bad ones.
"Tomorrow is a new challenge, the Champions League against a good team. I have good and bad memories from here in England, it's a challenge and if you provoke the fans they really side with the team and it becomes difficult, but we have our game plan.
"(Salah) has enormous quality, I remember he went through Basel, Chelsea, Roma and now Liverpool. He has grown and is fantastic in front of goal, he is now a legend. We will have to give our all to stop him."
