Wijnaldum limped out of the Netherlands 1-0 World Cup qualifier defeat against France on Monday night.
In the 61st minute, the midfielder went down clutching his right hamstring and was replaced by Sporting Lisbon striker Bas Dost.
He was sent for scans on his return to Liverpool to determine the extent of the injury.
And the Liverpool Echo claim the scans show the Dutchman has actually suffered a hip injury.
The report claims no timescale has been set on a possible comeback for the 25-year-old.
But the Reds have not yet ruled the midfielder out of the huge match with United on Monday.