But Klopp confirmed at a news conference that Mignolet will be in the first XI when Chelsea arrive at Anfield for Wednesday's third-round game.
"The only position I will confirm that we will change is Simon will start," he said.
"All the rest, you have to wait, but it will be a good team, believe me."
Klopp went on to praise Mignolet's application and hard work while accepting his new reality as understudy to the second-most expensive goalkeeper of all time.
"He has been brilliant. As you can imagine, transfer window time is one of two moments in a year when you can make a decision about going somewhere or bringing someone in," said the German.
"Simon would have been ready to go to another club as the number one but we couldn't do it. Since then he's [been] brilliant.
"He trains fantastic and he deserves this game. I am really glad to give him this opportunity."
Virgil van Dijk is unlikely to be risked after aggravating a rib injury during Saturday's 3-0 Premier League win over Southampton and might be replaced at centre-back by Dejan Lovren – the Croatian World Cup finalist now back in full training following a pelvis problem.
"Dejan looks actually quite good," Klopp said. "He trained completely four times now and he had a very intense period before that with the fitness guys, 10 days or so. He looks ready."
With regards to further injury updates, Klopp added: "Divock Origi is not far away but it's an ankle thing, a very unfortunate situation, and we will be very careful.
"Adam Lallana trained with the team, not a full session but he will come back step by step. For Chelsea I do not know but it will not be long. He is in a good way."