The unusual structure exists to work around Premier League regulations that prevent a club from loaning more than one player from the same top-flight side in a single season — Chelsea already have defender Axel Disasi on loan at Crystal Palace.
To get around the rule, Chelsea have agreed to defer their signing of Ahanor until next summer, with Atalanta retaining his registration and loaning him to Palace themselves in the meantime. Chelsea carry no risk in the arrangement: the £40m fee is contractually committed regardless of how Ahanor's loan season unfolds.
Ahanor only joined Atalanta from Genoa a year ago, in a deal reported at €16m plus €4m in add-ons, and quickly established himself as a first-team regular, making 28 Serie A appearances last season and making his Champions League debut in a 2-1 win over Club Brugge. His form earned him a first call-up to Italy's senior squad in May, for friendlies against Luxembourg and Greece.
Chelsea's interest in Ahanor first became apparent when they signed fellow young Italian right-back Marco Palestra from Atalanta in July, a move that appears to have opened the door to this second, more elaborate deal.
Primarily a left-back, Ahanor arrives at Palace as potential cover following a serious knee injury to Chadi Riad that is expected to keep the Morocco international sidelined for most of the season.
"I'm very happy to be here and to be a part of this great family," Ahanor told Crystal Palace's official website after completing the move.
"To be at one of the best clubs for young players in the Premier League is something which makes me grateful and excited."
The 18-year-old, who counts Paolo Maldini as his footballing idol, will spend the season on loan at Selhurst Park before completing his switch to Stamford Bridge in the summer of 2027, giving Chelsea a long-term option in defence while allowing him to continue developing regular first-team football in the interim.
He becomes Palace's third loan arrival from a Premier League club this summer, following Disasi, and represents a significant piece of business for a Genoa academy graduate who was playing under-17 football for the Ligurian club as recently as 2023.