Leicester have decided against going to the Court of Arbitration for Sport in a bid to get Adrien Silva playing for them before January.
Leicester and the Football Association asked Fifa to ratify the transfer of paperwork for Silva's £22million deadline day move from Sporting Lisbon after the paperwork was submitted 14 seconds late.
But Fifa rejected the request for Silva to be registered and he cannot play for the Foxes until January.
Leicester considered an appeal to CAS over the transfer saga but have now opted against that move, and while Silva will continue training with the club he will not be able to make his debut until the New Year.
A Leicester statement read: "It was our intention to submit an application to the Court of Arbitration for Sport for expedited proceedings so that the matter could be resolved as quickly as possible.
"However, it has been made clear to us that Fifa will not support an expedited process, forcing the club to reluctantly accept the single-judge ruling of Fifa's Players' Status Committee without reasonable opportunity for independent arbitration that is timely enough to be effective.
"Our frustration at the denial of effective due process doubles our disappointment at the original outcome and while the club is now essentially powerless to continue to challenge the decision, we will continue to support Adrien in any personal appeal he wishes to undertake.
"We intend to register Adrien at the earliest opportunity.
"In the meantime, he will remain under our care, training with the squad under the supervision of our coaching, medical and sport science staff."
Leicester sacked Craig Shakespeare as manager last week with Michael Appleton taking over as caretaker.