Stephen Donald's proposed move to Bath is in doubt due to technicalities over his work permit.
The New Zealand fly-half, 27, was due to arrive at the Rec this summer from Super 15 side Chiefs.
But the All Blacks' website says he cannot obtain the visa as he has no UK ancestral links and has not started for the national team in over 18 months.
BBC Sport understands Bath are aware of the issues but are still hopeful the deal can be completed.
It is likely the club will go to appeal in a bid to get the decision overturned.
Bath agreed to sign Donald on a two-and-a-half-year deal in June and expected him to arrive after the World Cup in November.
But his omission from the New Zealand training squad means he is unlikely to play a part in the tournament and they hoped he would be available to start the Premiership season in September.
Injuries and the form of fellow fly-half Dan Carter has restricted Donald to just three appearances off the bench for the All Blacks in the last two years.