Roy Keane could be without Kenwyne Jones and Carlos Edwards for Saturday's game with West Ham.
Sunderland are currently embroiled in a dispute with the Trindad & Tobago Football Federation over the eligibility of the duo for a friendly against Jamaica on Wednesday.
The Black Cats have withdrawn the players from Francisco Maturana's squad, claiming that Jones is suffering with a virus while Edwards picked up a groin strain in the weekend defeat at Aston Villa.
However, they have refused permission for the T&TFF to conduct their own analysis into the injuries and as a result the Caribbean nation's governing body are now seeking verification from Fifa to implement the five day rule which would rule the pair out of Sunderland's clash with the Hammers at the Stadium of Light.
"The decision was taken after it appeared Sunderland were unwilling to co-operate and we were left with little choice," said T&TFF spokesman Shaun Fuentes.
"It means that neither of the players can play or train for five days from the day of the (Jamaica) game.
"The reaction to this has been that Sunderland are now making efforts to co-operate and we are waiting for a scan on Carlos.
"Why they couldn't do that in the first place, I don't know."