Atletico Madrid sensationally announced they had re-signed France forward Antoine Griezmann on a season-long loan from Barcelona.
In one of the most eye-catching moves on Europe's deadline day, Atletico secured the return of a player they sold for a reported €120 million in 2019.
In a club statement Atleti said the deal includes an option for either club to extend the loan arrangement by a year.
Barca's statement also added that the deal contained an obligation to buy Griezmann, with La Liga champions Atletico also paying the player's wages in full.
Local media reports in Spain put the purchase option at €40 million.
The deal had been thrown into doubt with neither side announcing the move before the midnight CET deadline.
Local media said the delay was caused by a problem with La Liga's transfer registration system, but the league confirmed they had received all relevant documentation in time and had not granted an extension for the deal to be completed.