Altidore, who was the only Black Cats star to feature in Brazil, will be afforded an extended break to refresh before returning to the Stadium of Light, and Poyet has been keeping an eye on the former AZ Alkmaar forward's condition and expects him to be fully fit when he rejoins his teammates for training.
He told the club's official website: "From the beginning, the doctor has been in touch with the US medical staff. In the beginning it looked bad but it got much better during the weeks and Jozy was nearly available for the last 16.
"If, say, the US had got through to the next stage, Jozy would have played a part. We know hamstring injuries are tricky and that you have to be careful not to come back too quickly.
"Jozy deserves his holidays now. We have an agreement as to how many days he will have after finishing in the World Cup. I am sure, if nothing goes wrong, that when Jozy is back with us for pre-season, he is going to be fit to start training without any problems."
Altidore managed just two goals in 39 games for Sunderland last term after joining for £6.5m last summer.