The Spurs defender fell awkwardly during his side's Asia Trophy defeat to Sunderland on Wednesday and his projected recovery is "just about on the deadline" to face Crystal Palace
|10/3||Tottenham are 10/3 with Bet365 to lose their opening Premier League match to Crystal Palace
Vertonghen was taken off the pitch on a stretcher but his manager is still hopeful that he could recover in time.
"Jan has had damage to his ligaments and he's going to be most likely out of training for two to three weeks," the Portuguese told the press, "so just about on the deadline for the first game of the season.
"Hopefully we can see a bigger recovery time with him. Hopefully we can have him back sooner."
The pre-season Asia Trophy clash in Hong Kong was reduced to 40 minutes per half because of torrential rain, with the condition of the pitch quickly deteriorating.
Villas-Boas admitted that he had been "concerned" by the surface, observing afterwards: "The pitch is always like that for this tournament. You can't change the conditions, they are extremely poor."