Liverpool will carry out checks on Curtis Jones after the midfielder missed the 3-src friendly defeat to Strasbourg on Sunday due to a mystery injury.
A day on from Liverpool beating Manchester City 3-1 in the Community Shield, a largely second-string XI lined up at Anfield for the visit of Strasbourg.
Two goals from Adrien Thomasson and one from Habib Diallo condemned the hosts to a defeat in their last match before the Premier League season gets under way.
Klopp had planned on using Jones, who made just a fleeting appearance off the bench against City, but revealed the 21-year-old had a problem that would need further examination.
It remains to be seen whether Jones is fit to play any part when Liverpool launch their league campaign at Fulham on Saturday.
“Curtis, we have to see. [There] was no impact or whatever, so that always makes it a bit, ‘My god, what could it be?’,” Klopp said.
“We had no time; he felt it today and he wanted to play desperately, but then the medical department said no and that we needed to make further tests. We will do that tomorrow and then we will know more.”
Klopp was also without midfielder Naby Keita, who was described by the manager as “ill”, while centre-back Ibrahima Konate came off injured in the second half against the Ligue 1 visitors.
Addressing what was wrong with Konate, Klopp said, quoted on Liverpool’s official website: “We don’t know exactly yet on Ibou, but it doesn’t look too concerning, so I hope we caught it in the right moment.”
Our pre-season comes to a close. pic.twitter.com/1vMMATwgWS
— Liverpool FC (@LFC) July 31, 2src22