Chelsea have confirmed the signing of World Cup-winning midfielder Enzo Fernandez on a deal until the summer of 2031. 

The Blues sealed a £106.8million swoop for the midfielder, agreeing to pay his full release clause, just before the transfer window slammed shut.

Fernandez, 22, is now the most expensive player to ply his trade on British soil — eclipsing the £100m outlay Manchester City made for Jack Grealish in 2021.

Chelsea have handed him the No5 shirt — the number made available by Jorginho's departure for Arsenal on deadline day. 

But in a strange turn of events, he will not be allowed to wear that shirt in the Champions League as UEFA do not usually allow two players to don the same one at a club during a season.

Speaking to his new club's website, Fernandez said: "I am grateful to Chelsea and its ownership for doing everything they could to make me a part of this project. 

"I’m happy and excited to join the pride of London, to play in the best league in the world and to compete for the biggest trophies. 

"I can’t wait to play in front of our fans and help my teammates on and off the pitch."

In a social media post addressing his former side, he added: "I am grateful to God for giving me the opportunity to play for one of the biggest clubs in the world, where I enjoyed every moment to the fullest and always gave my best.

"Let the press not stain what we built together because it was something wonderful that I had never imagined.

"Thanks to all the collaborators who worked hard to make the institution much bigger than it is.

"Thanks to my colleagues for always treating me in the best way and making me feel at home.

"I'm grateful to the club's leadership and especially to [Benfica coach] Roger Schmidt, to all your staff for the trust and daily respect."

The River Plate academy graduate joined Benfica last July but rose to prominence when helping Argentina lift their third World Cup in December, with his performances seeing him named the Young Player of the Tournament in Qatar.

Chelsea had pursued him throughout January but a deal looked unlikely due to the Portuguese side's reported demands over the structure of the deal.

Yet after rekindling their interest in recent days, the Blues made a late breakthrough to add Fernandez to Graham Potter's bulging squad.

He follows the likes of Mykhailo Mudryk and Benoit Badiashile in joining Todd Boehly's revolution as the club's eighth major arrival during the January window.