Liverpool's Mohamed Salah was stretchered off with a head knock during the 3-2 win at Newcastle on Saturday leaving manager Jurgen Klopp sweating on the Egyptian's fitness ahead of next week's Champions League clash with Barcelona.
Salah was caught by Newcastle goalkeeper Martin Dubravka as they challenged for an aerial ball 20 minutes from time at St. James' Park.
"We'll have to see. He took a blow to the head. He watched the game in the locker room, he was OK, but we have to do more tests," Klopp told Sky Sports.
Salah had earlier scored his 26th goal of the season to put Liverpool 2-1 in front, but Salomon Rondon levelled early in the second-half to make it 2-2.
Divock Origi then headed Liverpool's late winner as the team went back to the top of the Premier League.
Liverpool host Barcelona in the second leg of their Champions League semi-final on Tuesday, trailing 3-0 from the first leg.