Chelsea have completed the signing of goalkeeper Kepa Arrizabalaga from Athletic Bilbao for a world-record fee of £72million.
The 23-year-old has put pen to paper on a seven-year deal at the Blues and will be the club's No 1 following .
The deal for Kepa outstrips the £66.8m paid by Liverpool for Alisson last month. The Brazilian was Chelsea's first choice to replace Courtois, but he was keen to work with .
On moving to Stamford Bridge, Kepa said: 'It's a very important decision for me, for my career, and also for my personal life.
'So many things attracted me to the club, all the titles the club has won, the other players, the city, the English Premier League.
'It's an accumulation of things, and I am very glad Chelsea has decided to trust me and to take me in as well.'
Director Marina Granovskaia added: 'Kepa is a talent we have admired for a long time and we are extremely excited about his arrival.
'He has already demonstrated fantastic quality and consistency and will be a big part of any success Chelsea have in the coming years.
'His long-term contract reflects the belief we have in him and we look ahead to the coming seasons with an enormous sense of optimism.'
Earlier on Wednesday, Real Madrid confirmed the signing of Courtois from Chelsea for £35million on a six-year deal.
Kepa almost joined Madrid himself in January only for the deal to fall through with his price at just £17.5m. Serie A side Napoli, then under the guidance of Chelsea boss Maurizio Sarri, also expressed an interest.
Madrid instead decided to keep the door ajar for Courtois after he showed a willingness to join them. As a consequence, Kepa was rewarded with a new £60,000-a-week contract at Athletic but saw his buyout clause rise to £72m.
Though young and relatively raw, 6ft 3in Kepa is regarded as one of the best prospects to emerge from Spain and was named in his country's World Cup squad.
Kepa is in contention to make his Premier League debut away at Huddersfield on Saturday and will train with his new team-mates on Thursday.
In July, Allison became the most expensive goalkeeper in history after Liverpool paid Roma £65million to land Brazil’s No 1.
With Arrizabalaga becoming world’s most expensive keeper yet, we take a look at other keepers who have broken the transfer records before.
1. Ederson, Benfica to Manchester City in 2017, £35million
Alisson’s countryman became the most expensive keeper (in pounds) when he joined City last summer. The 24-year-old quickly established himself as Pep Guardiola’s first choice and impressed throughout the season, both with his shot-stopping and distribution, as City coasted to the title.
2. Gianluigi Buffon, Parma to Juventus in 2001, £32.6million
The Italian (who remained the most expensive keeper in euros prior to Alisson’s move) was considered a pricey upgrade on the similarly great Edwin van der Sar when, aged 23, he left Parma. Seventeen years later his stay in Turin has finally come to an end, with Buffon moving to Paris St Germain. In an era when there has been significant competition from Iker Casillas in particular, Buffon will likely be remembered as the greatest keeper of his time.
3. Jordan Pickford, Sunderland to Everton in 2017, £30million
The most expensive English goalkeeper is 24-year-old Pickford, who grew stronger during his maiden season at Goodison Park after bursting onto the scene at Sunderland. He will start the new season with his reputation – and value – significantly enhanced by a stellar showing for England at the World Cup.
4. Bernd Leno, Bayer Leverkusen to Arsenal in 2018, £22million
Leno ended seven years at Leverkusen by signing for the Gunners, where he will hope to replace Petr Cech as number one, in June. The 26-year-old made more than 300 appearances for Leverkusen and was the youngest German goalkeeper to play in a Champions League match when he faced Chelsea in September 2011. Missed out on the Germany World Cup squad.
5. Manuel Neuer, Schalke to Bayern Munich in 2011, £19million
Widely considered the best keeper in the world for a number of years, the 32-year-old is renowned for his abilities not just with his hands but also his feet. Neuer won the Champions League with Bayern a year before helping Germany to victory at the 2014 World Cup. Spent most of last season on the sidelines because of a foot injury.