Liverpool midfielder Philippe Coutinho will have a scan on his injured ankle on Monday amid fears of ligament damage.
The Brazilian broke down in tears holding his ankle after challenging for the ball with midfielder Didier Ndong during the Reds' 2-0 win over Sunderland at Anfield.
He was taken off on a stretcher with protective padding around the damaged area on 33 minutes with Divock Origi replacing him in the victory that briefly had the Reds at the Premier League summit.
Coutinho was at Liverpool's training ground on Sunday for an initial assessment and left in a protective boot and on crutches, according to Sky sources.
"We have to wait for the scan. What we know it is something with the ankle," Liverpool manager Jurgen Klopp said.
"He had pain. Pain gets better. In the first moment it was very painful but at half-time he said it was better. I am quite an optimistic guy so I hope he can train [on Sunday]."
Coutinho has been one of the Reds' stand-out performers this season with six goals and five assists.
Klopp also confirmed Roberto Firmino had also sustained a knock which led to his late substitution, adding: "He is much better than Phil, but has pain in the calf."
A calf problem was also the reason Liverpool were without Daniel Sturridge for the Anfield encounter, with the striker reporting tightness in the muscle.
Klopp said: "He had a tight calf. He hasn't trained for two days and I have no idea when he is back. It is not sure that he can train tomorrow, so he was out because of this injury."
These injuries will be a growing concern for Klopp who is already without Adam Lallana due to a groin injury.
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