Rangers are expected to learn at the start of next week whether Fifa will authorise Daniel Cousin's £3million transfer to Fulham.
Fifa have still to pass judgement on the case involving the 30-year-old Gabon striker.
Cousin played 20 minutes of a French league match before joining Rangers from Lens in August, and Fifa rules stipulate players cannot appear for three different clubs in the same season.
A Fifa spokesman told Rangers' official website: "The outcome is still pending because the legal department have asked to see more documentation, especially from Fulham.
"They need more time to analyse everything and I don't think we will announce a verdict before Monday now."
If Fifa authorise the transfer, it will be allowed to go through despite the January window closing.