It will be the first time Lallana has faced Liverpool since his summer departure.
"It's hard to miss Adam Lallana because prett ymuch everyone in the squad is still in touch with him," said Klopp.
"But not this week. I would expect him to be on the pitch tomorrow, and we will put the friendship to the side, but after the game we will be friends again."
On Brighton, he continued: "I have analysts who are really honest and if they think the opponent is a tough one to play they tell me in the first moment.
"They said they are in a really good moment even if the results don't look like it. They have a lot of possession, they are a football side with a good idea.
"They haven't scored often enough to get results but we cannot go there and expect them not to finish their situations off. They make the pitch big. It's hard work and we have to be ready for it."