The Danish playmaker picked up the knock while away on international duty.
He lasted just 40 minutes of a friendly date with Norway on Friday before being forced from the field.
Eriksen hobbled off and watched the remainder of the game from the bench with an ice pack strapped to the problematic joint.
The 21-year-old will return to London to be assessed by Spurs' medical staff, but the outlook does not look good.
Denmark coach Morten Olsen believes Eriksen could be out of action for the foreseeable future, forcing him to miss the busy festive period.
He said: "We don't know if he's out for four or six weeks or how long it will take.
"It's bad for him at a new club."
Eriksen, who joined Spurs from Ajax over the summer, is poised to miss important games at home and in Europe.
Tottenham are due to face Manchester City, Manchester United, Liverpool and Southampton in the Premier League before Christmas, while they will also take in Europa League contests against Tromso and Anzhi Makhachkala and a Capital One Cup quarter-final with West Ham United.