The Londoners have made contact with his Portuguese club FC Porto to register their interest in the 16-year-old starlet.
Cassama is an attacking midfielder who has caught the attention of several top European clubs, including Premier League giants Manchester City.
But it seems Tottenham are eager to win the race for his signature, despite the uncertainty surrounding the future of manager Tim Sherwood.
Sherwood has found himself under pressure after consecutive defeats to Chelsea, Benfica and Arsenal, but insists he will have the final say on new signings.
Speaking ahead of their Europa League last 16 second leg clash with Benfica, Sherwood said: “Nobody else will come in here unless I sanction it. You can’t work any other way.
“The manager has got to work with the players so, unless he gets the players he wants, it’s always going to be an uphill task. He will always have the excuse of, ‘Well, they’re not my players’.”
Cassama is a Portugal youth international, and was snapped up from Sporting Lisbon last year.