Mane, who has scored six goals this season, hobbled off in the second half at Stamford Bridge.
“It was a knock on the bone, around the knee, and a dead leg – that’s an awful combination,” Klopp said.
“He tried everything, but I think you saw, there was one counter situation when he really tried and I would say on a non-dead-leg day he will get that ball, but no chance.
“And then we say, ‘Come on, now we have to do it,’ and [substituted him]. That’s it.”
Chelsea put up a fight in the second half, scoring through N’Golo Kante, but just fell short.
Blues manager Frank Lampard said: “Emerson is a similar injury to what he had, with a muscle. When you do that it means you have come back too soon.
“That is not a slight on Emerson, everyone wants to play this game to fair play. But those things shouldn’t happen.
“Christensen is a bang on the knee, which we need to assess. It was a shame to use up the two subs in the first half.
“I can’t give you any more than that – the doctor will assess. The first thought is that it’s not too bad, but we will see.”
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