FIFA rejected Leicester City's application to register Sporting Lisbon midfielder Adrien Silva as they reportedly missed the cut-off point by 14 seconds.
The Foxes had hoped to sign the Portugal international for £22m after an agreement was reached between the two clubs on transfer deadline day.
It was announced late on Tuesday night that world football governing FIFA had blocked the move, however, as despite being granted a two-hour extension the correct paperwork was still not submitted in time.
According to BBC Sport, the 2016 Premier League winners were a matter of seconds too late to formally register the player as their own, likely leaving him ineligible until January.
City are expected to appeal the decision, having sanctioned fellow midfielder Danny Drinkwater's move to Chelsea on the same day.
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