David De Gea's £29m move from Manchester United to Real Madrid has collapsed because the necessary paperwork was not submitted in time.
No official announcement has yet been made by either club.
As part of the deal to sell De Gea to Real, United were planning to bring Keylor Navas in the opposite direction.
There is no precedent for Spanish clubs being given additional time to conclude transfers as there is in England.
Blame for the failure to complete the deal is already being apportioned.
Reports in Spain claim United were responsible for the deal collapsing.
The line is they did not get their paperwork to Spanish Football Federation headquarters until a minute after the 23:00 BST deadline.
United say they have a receipt that proves they submitted the relevant documents in time.
It remains to be seen whether Real will appeal to world governing body Fifa, which is responsible for sanctioning international transfers.