Liverpool face an anxious wait for news on captain Jordan Henderson after he was substituted as a precaution during their 1-0 Premier League win over Sunderland.
Henderson has been troubled by a persistent heel injury this season and, although the nature of his new injury is unclear, should it be related to his previous issue it would be a huge worry for Liverpool.
The skipper played an hour of Wednesday's clash at the Stadium of Light before being replaced by Lucas Leiva, but Jurgen Klopp remains unsure over the extent of his midfielder's problem.
"I don't really know," said the German. "It's not perfect otherwise we wouldn't have taken him off, but we had to.
"Now we have to wait. I cannot say exactly [what the injury is] at this moment. I hope it's not too serious."
Henderson has only featured seven times for Liverpool in the Premier League this season due to plantar fasciitis, a problem that he has been told is incurable by the club's medical team.
