New Chelsea signing Enzo Fernandez has praised the club's hierarchy for breaking the world transfer record to bring him to Stamford Bridge.

The Blues confirmed on Tuesday morning that World Cup-winner Fernandez had completed his British record £106.8million (€120.5m) transfer from Benfica after negotiations went to the final hours of a dramatic transfer deadline day.

Benfica were first to announce the signing overnight and Chelsea hailed Fernandez's capture on Wednesday morning.

"I am grateful to Chelsea and its ownership for doing everything they could to make me a part of this project," the 22-year-old told the club's official website.

"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 team-mates on and off the pitch."

The PA news agency understands that Fernandez underwent a medical in Lisbon on Tuesday evening as the clubs worked towards an agreement, with divisions relating to the instalments in which the fee will be paid taking the deal down to the wire.

Fernandez becomes the eighth signing of a frantic window for the Blues, with a total January spend by owner Todd Boehly of around £318m (€358m).

"In Enzo we are signing a World Cup-winner and one of the brightest talents in global football," said Boehly.

"We are excited to add him to Graham's (Potter) squad and we are sure he will form an important part of our team going forward.

"Enzo has demonstrated his ability at the very highest levels so we're looking forward to seeing what he will do in Chelsea blue!"

Fernandez, who won the Silver Ball for best young player during Argentina's triumphant World Cup in Qatar last year, has signed an eight-and-a-half-year contract, in keeping with the club's policy this season of signing players on lengthy terms in order to spread their outgoings and remain within UEFA's Financial Fair Play rules.

Fernandez lifts the World Cup

It takes the Blues' spending since Boehly bought the club last May to more than £550m (€619m), though PA understands that UEFA is set to close the loophole that has allowed for such a large outlay by limiting the length that such deals can be spread over to five years.

It has been a meteoric rise to prominence for Fernandez, who joined Benfica from from River Plate in Argentina only seven months ago for £8.8m (€10m), but his stock soared after a successful start to the season in Portugal's Primeira Liga, leading him to command a British transfer record fee after just 29 games for the Lisbon side.

He shot to global attention as his country became world champions for the third time in December, beginning the tournament as a substitute but breaking into the team after scoring against Mexico and starting every subsequent match, including the final against France in Lusail. He had made his senior international debut for Lionel Scaloni's team as recently as last September.

Having negotiated unsuccessfully with Benfica earlier in January, Chelsea were reportedly persuaded to return with a new bid after it emerged UEFA plans to introduce maximum contract terms starting with the next transfer window.

At present, the fee can be recorded in the club's annual spending figures as being spread over the length of the player's contract, freeing the club up to negotiate higher fees. Five-year maximum terms will mean transfer fees must be spread over a shorter period, limiting the total that can be spent.

The club have taken full advantage of the loophole during Boehly's tenure, with January's outlay adding to the more than £250m (€281.5) spent last summer.

Defender Benoit Badiashile signed from Monaco for a reported £35m (€39.4m), England Under-21 international Noni Madueke joined from PSV Eindhoven for £29m (€33m) whilst Ukraine winger Mykhailo Mudryk was snatched from under the noses of Premier League leaders Arsenal for £88m (€99m).

Portugal international Joao Felix signed on loan from Atletico Madrid, and French right-back Malo Gusto joined from Lyon before being loaned back to the Ligue 1 side for the rest of the season. David Fofana from Molde and Andrey Santos from Vasco de Gama complete an outrageously ambitious window for Boehly and the club.