Hull FC head coach Lee Radford fears new signing from rugby union Tom Biggs could face a delay in switching to the Super League club.
Bath and England Saxons winger Biggs, 29, who was born in East Yorkshire, has signed until the end of 2016.
But Radford said it was possible Bath could retain Biggs to give them cover during the Six Nations tournament, which runs until mid-March.
He told BBC Radio Humberside: "It would be a massive blow."
Biggs is one of seven new signings made by Hull in preparation for the 2014 season. As a newcomer to the 13-man code, however, Biggs will need as much time as possible to prepare and adjust.
Radford continued: "Hopefully he will be here before [the season starts in] February, which would be a bonus for us. But it's a real difficult one, he's never 'played a ball' in his life, I don't think, so it will be real interesting to see how he goes.
"Hopefully he'll take to the game. One thing in his favour is he's energetic in the way he plays, he's really enthusiastic, and hopefully he can take that into our code."
No-one at Bath Rugby was available to comment.