Chelsea has signed Mateo Kovacic on a season-long loan from Real Madrid, with goalkeeper Thibaut Courtois expected to have his permanent move in the opposite direction confirmed later on Thursday.
Midfielder Kovacic, 24, has been at Real for three seasons since joining from Inter Milan.
He helped Croatia reach the final of this summer’s World Cup in Russia.
“I am really happy and excited to be here. It is an amazing feeling,” Kovacic told Chelsea’s website.
“I will try to do my best for this club. It is a new league for me, the beginning is always tough but I am sure the coach and my new team-mates will help me and I am looking forward to a great season.”
Chelsea director Marina Granovskaia added: “He is a perfect fit for us this season, his style is well suited to how Maurizio wants to play and we are sure he will prove to be a valuable asset for the club.”
Kovacic joined Real in the summer of 2015 and helped the club win three Champions Leagues in a row in his three seasons at the club.
He is the second-youngest player to have ever scored in the Champions League after netting against Lyon at just 17.
Real plan to present Belgian Courtois, who will sign a six-year deal, as their new signing at 12:00 BST.
The Blues say the deal is still subject to Courtois agreeing on personal terms and completing a medical, although Real have announced him as their player on their official website.
Courtois has been a Chelsea player since 2011 when he signed from Genk.
He was immediately loaned to Atletico Madrid, where he played until 2014, before returning as the Blues’ number one.
On Monday he was absent from Chelsea’s Cobham training ground, where he was due to take part following his involvement at the World Cup.
Courtois was voted best goalkeeper at the tournament, with Belgium beating England in a third-place play-off.
Chelsea have signed Kepa Arrizabalaga from Athletic Bilbao as his replacement for £71m – a world record for a goalkeeper.
The deal for the 23-year-old surpasses Alisson’s £66.8m July move to Liverpool.
He is Spain’s number two behind Manchester United’s David de Gea and has one international cap.