A disappointed Leicester City say they may appeal FIFA's decision to reject Adrien Silva's registration with the club.
The Foxes were in the process of completing the paperwork for the 28-year-old £22m Portugal international, but missed the August 31 deadline by 14 seconds.
Leicester's appeals to FIFA were thrown out by the world governing body, but the Foxes feel they have a legitimate case for the player and could turn to the Court of Arbitration for Sport.
A statement from the club read: "We cannot hide our disappointment or that of the player at the short-term consequences of the decision.
"We maintain, and have made strong representations to Fifa's Players' Status Committee, that all parties involved in Adrien's transfer fulfilled their obligations, consistent with Fifa regulations and within the required timeframe.
"The club is reserving its position in relation to whether it will decide to appeal the decision to the Court of Arbitration for Sport."
If they fail, Silva will only be able to play for Leicester when the transfer window reopens in January.