The Tottenham midfielder could not be heading to Watford this summer.
Stambouli was expected to seal a deal to move to Watford this week, but according to the London Evening Standard the transfer could fall through.
The report states that the £5.5 million move, which has been agreed by both clubs, is yet to be officially confirmed as Stambouli is considering his options.
He has already held personal term with the Hornets, and it is believed that he was keen on securing a move to Hertfordshire.
However, the midfielder has yet to put pen to paper, and this deliberation has led to worries that he may pull out of the deal, despite seemingly being set to finalise the transfer.
There are no indications as to why Stambouli has yet to formally agree to the move, although it could be due to doubts over his playing time at Vicarage Road.
The Hornets have already signed two defensive midfielders, in Etienne Capoue and Valon Behrami, and as head coach Quique Sanchez Flores has been utilising a 4-2-3-1 system, it could be believed that Stambouli would not be a guaranteed starter.
As he wants to leave Spurs due to a lack of playing time, it is likely that he will only opt to move to a club where he is guaranteed first-team football.
Stambouli, 24, is still expected to leave Spurs this summer, as he pushes for a move away, and it will now be up to Watford to ensure they offer him agreeable terms if they are truly intent on securing the signing of the French midfielder.