Leicester City's bid to officially complete the £22m signing of Adrien Silva before January is hanging in the balance after they missed the deadline to register him by just 14 seconds.
Fifa have refused to accept Silva's registration after his move from Sporting Lisbon, five days after the deal and terms were agreed late on deadline-day.
And it has emerged that is because Leicester failed to register the player by a matter of seconds, meaning Silva is unlikely to be able to play for the club until the New Year.
Leicester insist they are still attempting to resolve the issue and are in dialogue with Sporting and Fifa, in a bid to push through the transfer.
Leicester moved for Silva after agreeing to sell Danny Drinkwater to Chelsea for £35m but asked for a two-hour extension from the Football Association to finalise the paperwork.
A Leicester spokesman said: "We are working with Adrien and Sporting Clube de Portugal to overcome some issues relating to the player's registration and exploring all options to find a resolution."
Silva left the Portugal national team to fly to England to have talks but the deal was delayed as Leicester were still in negotiations with Chelsea over the fee for Drinkwater.
Meanwhile, Riyad Mahrez is to hold talks with Leicester officials on Thursday, after his bizarre attempts to force a move on deadline day.
Mahrez will return to training later this week after international duty with Algeria and is expected to be included in the squad for Saturday's home game against the champions.
Leicester were bemused on deadline-day when the £50million-rated winger left Algeria's squad in the hope of securing a move away, though no bids had been received.
But manager Craig Shakespeare will speak with Mahrez and reiterate that he expects the 26-year-old to be professional while he is still a Leicester player.