Neymar, the world's most expensive footballer, may have to wait until after Paris Saint-Germain's trip to Guingamp on Sunday to make his debut for the club.
Brazil international Neymar's world-record €222 million move went through last week and he was unveiled at the Parc des Princes before Saturday's Ligue 1 win over Amiens.
But he was unable to make his PSG debut that day because his international transfer certificate had not been received by the Ligue de Football Professionnel (LFP) from Spain's La Liga.
L'Equipe reported that the LFP had still not received the paperwork on Monday.
That means it is possible it may not arrive in time for Neymar to play at Guingamp, with the 25-year-old postentially having to wait until Toulouse visit Paris the following weekend.
L'Equipe reported that the Spanish FA (RFEF) have 15 days from Aug. 3, when Neymar joined PSG, to send the documentation to Liga officials for forwarding to France.
If that does not happen by midnight on Aug. 18, world football's governing body FIFA would be required to get involved.
Le Parisien reported that FIFA could be called upon as soon as Thursday -- one week after Neymar's arrival -- and that could delay the issue by an extra 10 days.
Reports in both France and Spain have suggested that the delay is coming from the Spanish side.
When contacted by ESPN FC, La Liga said "it is the RFEF's responsibility to send the papers" before they can be forwarded.
ESPN FC requested comment from the RFEF and the LFP, but neither has so far responded.