The club has activated an option with the FA that could see them play home games at Wembley up until the new year. Initially they had been due to play only one game at the national stadium before moving into their new home on September 15th.
It is understood that the club are still working hard to ensure they meet the September deadline, but concern over the project is growing.
The club have had to make a payment to the FA as part of the deal, but it does at least give them an option should they need to take up use of Wembley again. It would also have to be used in their Champions League group stage clashes.
"I don't think you should underestimate what a huge task we took on in order not to have a second season at Wembley," Tottenham's executive director, Donna Cullen said last month.
However, it looks as if her words may have been premature.