Southampton could be set for a legal battle with Atletico Madrid over a permanent deal for Belgium defender Toby Alderweireld.
The 26-year-old was on loan at St Mary's last season with an option to make the deal permanent for £6.8m.
Atletico could have paid £1.5m to buy back that clause and instead sell Alderweireld to the highest bidder.
But Southampton believe that the timeframe for Atletico to take that option has now elapsed.
Alderweireld, who made 26 Premier League appearances for Southampton, is reported to interest Tottenham and Manchester City.
In May, the 43-cap international expressed his desire to stay in the Premier League next season.
Southampton manager Ronald Koeman has also spoken positively about completing a permanent deal for the defender.