Sunderland are still waiting to discover the extent of the injury suffered by Kenwyne Jones in Trinidad & Tobago's friendly with England on Sunday.
The powerful striker, who netted eight goals for the Black Cats last season, is thought to have sustained knee ligament damage in the early stages of the 3-0 defeat in Port of Spain.
Jones was involved in a heavy collision with England goalkeeper David James.
The former Southampton striker has definitely been ruled out of Trinidad & Tobago's friendly against Jamaica on Saturday and is now on his way back from the Caribbean to Wearside.
"Kenwyne is returning to Sunderland and the nature of his injury will be assessed by the club's medical team," confirmed a club spokesman.
The £5million signing had only just returned to action after missing the final Premier League game of the season with a fractured wrist.