Kaboul earns around £35,000 a week and, if a new contract had still not been agreed by January, he would be free to talk to other clubs abroad.
Spurs would be loath to lose the player for free but Kaboul's case would be strengthened if he could string together a series of matches without suffering any setback, says the London Evening Standard.
"It's a bit of a problem because of his injury in the knee it has taken him time for his body to adapt to new positions on his run," said Villas-Boas.
"Because of that he's putting extra strain on his muscles and keeps getting small contractions that limit him finishing the games."
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