Arsenal and West Ham United insist Declan Rice's transfer is on track.
The England midfielder is set to join Arsenal for a British record £105m this week.
The fee was agreed over a week ago, but the deal is yet to be rubberstamped.
Sky Sports says the delays have been caused because the Hammers are waiting on the Gunners to sign off on the final wording of the terms.
However, there is no danger of the deal collapsing.