The Sun says Lennon could be out for a month with a tear in his groin.
Tottenham's flying winger picked up the injury during Monday's 2-0 victory over West Ham.
It is a big blow to Spurs' tilt at the top four and he will miss the key Premier League clash at Champions League rivals Liverpool on January 10.
A club source said: "He will be out for a few weeks with the tear. It is not good news."