Liverpool are concerned Diogo Jota has suffered a major hamstring injury.
The Portugal international has only just returned to training after the issue arose during a UEFA Nations League match against Switzerland last month.
"Diogo, unlucky eh?" said Reds manager Jurgen Klopp ahead of their Singapore friendly against Crystal Palace on Friday.
Jota will be facing an injury scan to assess the extent of the setback.
"He had an injury from the end of last season. He trained fully yesterday but got injured again. That's really not cool.
"Now we have to wait for the results. He had an assessment this morning so we will have to see. It's in the same area," confirmed Klopp.