Tottenham may have to pay a huge extra fee for Micky van de Ven in the coming months.
Spurs signed the centre half for 43 million from Wolfsburg in the Bundesliga in the summer.
While coach Ange Postecoglou was delighted to get his main man, the club accountants may not be as pleased with the deal's structure.
German newspaper SportBILD states that chairman Daniel Levy agreed to insert a clause in the deal regarding Spurs' performances.
The London club would have to pay Wolfsburg 8.6 million if they qualify for next season's Champions League.
At the time, Spurs finishing in the top four (or five) in the Premier League was considered very unlikely.
But they are currently top of the table from rivals Arsenal on goal difference.
