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 said on www.rangers.co.uk: '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.