Tottenham manager Mauricio Pochettino has said the club will trigger an extension clause in Toby Alderweireld's contract.
The Belgium defender will now be contracted to Spurs until the summer of 2020, having been due to be a free agent at the end of the season.
However, by taking up the year's option it also activates a £25million release clause which runs from the start of the 2019 summer transfer window to the last two weeks.
The news comes several weeks after Spurs also triggered an option on Alderweireld's Belgium team-mate and close friend Jan Vertonghen's contract.
Pochettino said: "Yes, for sure. It is obvious. It is the same situation as Jan (Vertonghen)."
Alderweireld was expected to leave last summer as Spurs looked to cash in on him after he reportedly rejected a new long-term deal.
The 29-year-old barely played at the back end of last season, despite being fit after a hamstring injury, as Pochettino appeared to freeze him out.
He was reportedly on Manchester United's radar for much of the summer, but no deal happened and he has enjoyed a second coming at Spurs this season.
While Vertonghen and Davinson Sanchez have struggled with injuries this term, Alderweireld has been a mainstay of the side, making 24 appearances.