Lallana spent six seasons at Anfield prior to his summer free transfer move to Brighton on a three year contract.
Despite an injury hit spell with Liverpool, he was an integral figure at the club and helped them to the Premier League and Champions League titles.
Klopp previously hailed Lallana as one of the most influential players during his time as Liverpool manager and the German is looking forward to catching up with his former player as they travel to 16th placed Brighton for the Saturday 12.30pm kick-off.
The midfielder has made an encouraging start to his Brighton career but is in a race to be fit to face his old teammates after sustaining a groin injury in last Saturday's win at Aston Villa.
Lallana played the first 45 minutes at Villa Park and provided the assist for Danny Welbeck's well-taken opener. The 32-year-old didn't appear for the second half and was replaced by Dutch international defender Joel Veltman.
Albion boss Graham Potter said on Thursday that Lallana needs more time to prove his fitness for Liverpool and a late decision will be made on the former England international.
Klopp however expects his 'friend' to play and admits that he and most of the current Liverpool squad still keep in touch with their old colleague.
"It's hard to miss Adam Lallana because pretty much 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."
Klopp has been impressed with Brighton and received favourable reports from his trusted analysts.
Brighton have perhaps not always secured the points their displays have deserved but the Liverpool manager admits their style of play causes big problems.
"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," said Klopp.
"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."
The Liverpool manager has complained about injuries and a hectic fixture schedule ahead of the match and even said 'give Brighton the three points now' before their midweek Champions League loss to Atalanta.
The Reds are already without a number of first-team regulars, and Klopp made a further five changes against the Italians to the side that beat Leicester in the Premier League last Sunday.
Liverpool were clearly saving their big hitters for the Brighton match.
Klopp said it is now a “waste of time” him speaking out about fixture congestion and was in no mood to talk about the subject ahead of the Albion match.
“I’ve got 25 hours now to prepare for a game. Whatever I say doesn’t help so I’ll stop talking about it. It changes nothing. It’s just a waste of time,” he said.
“My thoughts are clear but this isn’t the time for me to speak about it. The last thing I want is to create a headline but you say I’ve given up.
“I speak in a general way. A general problem. Wednesday/Saturday 12.30, you have to ask other people why they do that. I don’t have the answer.”
Liverpool's injury problems are considerable as Naby Keita, Jordan Henderson, Xherdan Shaqiri, Joe Gomez, Trent Alexander-Arnold, Virgil van Dijk, Thiago Alcantara, Alex Oxlade-Chamberlain are all on the list.
Their skipper Henderson however is making progress from a thigh injury and has not been ruled out for Brighton.
"Hendo trained yesterday in parts of the team training and his own individual session so we have to see what we do with that," said Klopp. "All the other players that played are in recovery.
"That's how it is when you have so few days in between. So we have to make late decisions. If you asked me my line up, I couldn't tell you. I have to wait for medical department to tell me who looks like being ready."
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