Kevin Stewart suffers injury blow just days after making his Premier League debut.
The 22-year-old has been one of the main beneficiaries of Klopp's rotation policy in recent weeks, making four appearances in the FA Cup before Liverpool bowed out in a fourth round replay to West Ham United.
Stewart's impressive displays resulted in his manager handing him a Premier League debut on Sunday as he featured for the final 24 minutes of the 6-0 demolition of Aston Villa.
Klopp said: "We lost Kevin Stewart in training. He blocked a shot and his ankle was not stable. It was a bit bruised so we have sent him for a scan. We think it’s the ligament.
“He trained outstandingly and then this happened. That’s not too good.”
Providing that Liverpool make progress in Europe, Stewart could return to play a part later in the campaign, but the injury comes at the worst possible moment for a player who began the season being loaned out to League One club Swindon Town.