Eric Dier says his full-time switch to centre-back was a choice he made before Jose Mourinho replaced Mauricio Pochettino as Tottenham head coach.
Dier says he felt the time was right to drop from central midfield to his preferred position at the heart of defence before Mourinho's arrival.
The England international discussed his desire with former boss Pochettino and says Mourinho gave him his chance, which he has taken, following the defeat at Chelsea last season.
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The 26-year-old has become one of Mourinho's first-choice central defenders and has started five of England's eight internationals in that position this season.
Dier told Sky Sports News: "It was something we spoke about (when Jose Mourinho arrived). It was a decision I actually made before the manager arrived here.
"It was something on my mind for a while and I spoke with Pochettino over various seasons. I felt the time was right in terms of my age, in terms of what I done and my career.
"I felt I needed to make that commitment and move forward, I had the conversation with the manager when he arrived and he respected that.
"He said 'It's up to you'. After the Chelsea game last season where he lost, he said 'Now is your chance and you need to show me now'. I'm grateful for the opportunity to prove myself there. It is where I feel most confident."
Dier: Kane does it all!
Dier says he is grateful for the assistance Harry Kane has provided the back four, both in open play and on set pieces.
Kane's all-round game has caught the eye this season; he has scored seven goals, provided seven assists and has also been praised for his defensive contributions during Tottenham's opening 10 Premier League games this season.
"He does it all!" Dier added. "We are all completely committed. The defensive record is a group effort. It starts at the top and ends at the bottom.
"It's everyone willing to go that extra mile for each other, it makes the difference.
"The contribution Harry (Kane) makes from defensive situations and defensive set pieces, he is extremely effective from defensive set pieces and we are really grateful for the help.
"He knows the feeling you get from scoring a goal. Maybe he just wants to take it away from others."
'Being top only matters in May'
Dier says it is a nice sight to see Tottenham sitting top of the Premier League for the second week in a row but insists the squad are not getting carried away.
Spurs have wins over Manchester United and Manchester City this season and earned a goalless draw at Stamford Bridge against Chelsea, a fixture they lost 2-1 last season.
But Dier says Tottenham are still looking to improve and won't rest on their impressive start.
He said: "We know there is a lot of work to do, there is a lot we need to improve on.
"We need to keep moving in this direction we are going in and also understand there are going to be difficult times and be ready to handle those situations.
"It's easy when things are going well but when things take a turn for the worse, we need to be ready to handle those situations. It only really matters who is first in May.
'Arteta most exciting young coach in Europe'
Spurs face north London rivals Arsenal at the Tottenham Hotspur stadium on Sunday and Dier has heaped praise on under-fire manager Mikel Arteta ahead of the clash.
Arsenal are 14th in the Premier League table heading into the weekend after suffering five defeats from their opening 10 matches.
Dier still believes Arsenal are in good hands.
"They are going through a difficult period but these games it doesn't really matter who is where in the table," Dier added.
"We know how much of a difficult game it is going to be. The position in the table is irrelevant. It's early on in the season for both teams.
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"They have a lot of quality in their team. They have a very exciting young manager. The most exciting young manager in Europe for sure. I like his way, the way it seems to be. I think they are in good hands.
"We know they have a lot of quality in their squad and we will be very aware of that on Sunday."
Dier has launched a new app called Spotlas. Spotlas is a map based recommendation sharing social network where you can follow friends, family and influencers to see all of their favourite spots around the world.
It is a digitalised word of mouth experience that recognises that a single recommendation from someone you know and trust is infinitely more powerful than any number of anonymous ratings and reviews.
It is a platform entirely focused on making it quick, easy and reliable to find the spot for you no matter what the occasion or where you are in the world.
Dier will be discussing Spotlas and other topics at a Websummit event on Wednesday evening.