Chelsea have signed Atletico Madrid and Spain midfielder Saul Niguez on loan with an option to buy.
The 26-year-old was a key player as Atletico won La Liga last term, making 33 appearances.
Sevilla earlier confirmed that they had rejected Chelsea’s “unsatisfactory” offer for France defender Jules Kounde.
“I am very excited to start this new challenge with Chelsea,” said Saul, who was previously linked to Manchester United.
“Blues fans, I am one of you now and I can’t wait to wear the shirt, start training and see all of you. See you soon!”
Saul has played 340 matches for Atletico and scored 43 goals.
Elsewhere, Barcelona have signed Netherlands striker Luuk De Jong from Sevilla on a season-long loan after France’s Antoine Griezmann left the Nou Camp to rejoin Atletico Madrid on a similar deal.
Barca will pay 31-year-old De Jong’s salary this season and have an option to make his stay permanent next summer.
The 30-year-old returns to Atletico two years after he joined Barca for £107m.
The France striker scored 133 goals in 257 games for Atletico, winning the Europa League, Uefa Super Cup and Spanish Super Cup during his time in the Spanish capital.
But the 30-year-old scored just 35 goals in 102 games and managed to win only the Copa del Rey with Barca.
Last summer, Atletico signed striker Luis Suarez from Barcelona and he helped Diego Simeone’s side win La Liga.
Griezmann became the 11th player to leave financially struggling Barcelona this summer, including Lionel Messi.
Barcelona had to let their all-time top goalscorer leave to fit within La Liga’s wage structure, and Messi joined Paris St-Germain.
Griezmann was the third transfer deadline day sale from Barcelona. Right-back Emerson Royal joined Tottenham for £25.8m and teenage midfielder Ilaix Moriba moved to RB Leipzig for £13.7m.
The only money Barca spent to bring in a player on a permanent deal during the summer transfer window was to exercise their option to call Emerson back from Betis for a reported 9m euros, only to offload him for a substantial profit.
De Jong, who scored 19 goals in 93 games for Sevilla after moving to La Liga from PSV Eindhoven in the summer of 2019, is the fourth forward to join Barca this summer after compatriot Memphis Depay, Sergio Aguero and Yusuf Demir.
Having Sergio Busquets and Jordi Alba agree to salary reductions on Tuesday ensured Aguero could be registered and helped “to extend the club’s limit with regards to financial fair play regulations,” a Barca statement said.
Gerard Pique did the same earlier in the summer.
In France, Paris St-Germain have signed Portugal full-back, Nuno Mendes, on a season-long loan deal from Sporting Lisbon late on transfer deadline day.
The Ligue 1 side have the option to make the deal for Mendes permanent for a reported £34m.
PSG attacking midfielder Pablo Sarabia has joined the Portuguese side on a season-long loan.
It caps a successful window for PSG after signing Lionel Messi, Gianluigi Donnarumma, Sergio Ramos, Georginio Wijnaldum, Achraf Hakimi and Danilo.
Additional reporting from BBC