The Reds return to the King Power Stadium in Premier League action after goals from Shinji Okazaki and Islam Slimani dumped them out of the Carabao Cup at the same venue on Tuesday.
Lovren missed that match due to a back injury and Matip, along with Germany international midfielder Emre Can, sustained a knock.
"It's nothing major but it was enough to keep him out of two games and he is not in training so far, so that means he is also a doubt for the weekend. That's not too cool," Klopp said of Lovren's injury
"It's the same, but with completely different [injuries] for Joel Matip and Emre Can. They have little bits from the last game, so we have to see.
"Hopefully they can be back in training [by Friday], but it's not sure at the moment so we have to wait."
Today's Melwood session... pic.twitter.com/qL2WNvzpZW— Liverpool FC (@LFC) September 21, 2017
Can was pictured training later on Thursday but Liverpool could again line up with youngster Joe Gomez alongside Ragnar Klavan, who has failed to entirely convince at the heart of defence, as they try to break a run of four games without victory.
Familiar defensive frailties have come under the microscope during this period and Klopp believes his players' determination to do the right thing when under attack is leading to weaknesses in the next phase.
"It's concentration but it's also a little bit of readiness in these moments, the second ball situation," he explained.
"We've spoken about set-pieces since I've been here, more or less. In different moments we conceded goals from the first ball – cross, header; cross, volley.
"We sorted this, somehow, so far. We use the formation much better. But we cannot defend a set-piece with a 50-yard header so there will be an opportunity with the second ball. Fighting for these balls, we need to do differently.
"What we have at the moment, because of the situation, everybody wants to help where the first ball is. You see this very often, we come too close together in this situation and it means, for the second ball, we don't have a good formation."
"We will fight." pic.twitter.com/b3mppglyA3— Liverpool FC (@LFC) September 21, 2017
Nevertheless, Klopp would rather be trying to plug defensive gaps than struggling to encourage the attacking verve that Liverpool display in abundance at their best.
"We really work on this and we see it [the defensive mistakes] in the game," he added.
"Around these situations, there is not the same confidence as there is around, 'give us the ball'. That looks a lot more natural.
"Each manager in football has another hole to fill, but if you ask me what I would prefer – do you want your team perfect in defending set-pieces but they cannot play football, or would you prefer the other way around? I still would take this one. We are on it, as you can imagine."