Chelsea have signed Saul Niguez on loan from Atletico Madrid with the option to make the move permanent next summer.
A loan fee in the region of £3.5m has been agreed, with the option to buy set at around £30m.
The Blues have bolstered their midfield on deadline day with the Spain international providing another excellent option for Thomas Tuchel.
Saul said: “I am very excited to start this new challenge with Chelsea. 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!”
Chelsea director Marina Granovskaia added: “We welcome Saul to the Club and believe he completes our squad as we compete for honours in five different competitions this season.
“He is a proven winner, a player with huge experience and we know he will be very well-suited to the challenges that face us on all fronts in the coming year.”
The 26-year-old, who is under contract at the Wanda Metropolitano until 2024, fell down the pecking order under Diego Simeone following the signing of Rodrigo de Paul this summer.
After starting the first two La Liga games of the season, Saul dropped to the bench for the 2-2 draw against Villarreal before coming on as a second-half substitute.
Saul, who has 19 caps for Spain, joins up with compatriots Cesar Azpilicueta, Marcos Alonso and Kepa Arrizabalaga at Stamford Bridge.
