Centre-back Kevin Wimmer has signed a new five-year contract at Tottenham.
The 23-year-old Austria international joined last summer from FC Koln for a fee in the region of £4m, signing a four-year contract, and has now committed further until 2021.
He said: "I'm delighted. It's a big pleasure for me and it's a dream come true that I can stay so long with such a big club.
"I called my mum and dad to tell them and of course they are also very happy. It's special for them because they know we always hard work, we train every day and the season is very long.
"The first year here was very good for me, I could learn a lot. The first few months were a little bit difficult because London is such a big city and you have to get to know everything, but after two or three months everything was easier. It's one of the best cities to live in."
Wimmer impressed in place of the injured Jan Vertonghen last season and is set to begin the new campaign as the left-sided centre-half after Vertonghen picked up another injury with Belgium at Euro 2016.
Several German clubs have been interested in taking him back to the Bundesliga due to his limited playing time last term, but he has a long-term future at White Hart Lane.
Spurs boss Mauricio Pochettino wants to have two left-footed and two right-footed centre-halves in competition for first-team places, and he sees Wimmer as a model deputy to develop under the more experienced Vertonghen.
Wimmer made 21 appearances in total last season including nine Premier League starts and six in the Europa League.
He began his career with LASK Linz in Austria before joining Koln in 2012 and making 32 appearances in the Bundesliga.