Albian Ajeti is open to leaving West Ham on loan for the rest of the season but is hamstrung by UEFA rules.
The 22-year-old, who is understood to be frustrated at a lack of first-team opportunities since signing from FC Basel in the summer, has already played competitive matches for two clubs this season.
That leaves his options for a potential loan switch in January drastically short - able only to join a team in a league starting a new season in the New Year such as Sweden, the USA or Japan.
A string of European clubs are understood to have made offers to take him on loan without realising it would not be possible to register him until the 2020-21 season.
Ajeti is yet to start a Premier League game for West Ham following an £8m move in August, making five sub appearances in the league and two starts in the Carabao Cup.
How to follow the January transfer window
Sky Sports will bring you the very latest news from the January transfer market with the return of three shows.
Start your day with Good Morning Transfers at 9am as our team of reporters bring you the latest news and insight. Transfer Talk then follows at midday delivering analysis of the biggest stories. Then join us at 7pm for the definitive round-up of the day's news with The Transfer Show.
Meanwhile, the Transfer Talk podcast will also be back at the turn of the year with more expert analysis from here and across the continent.
And as well as tuning into Sky Sports News, don't miss a thing with our dedicated Transfer Centre blog.