CHELSEA star Ian Maatsen has agreed to join Borussia Dortmund on loan, according to reports.
However, the left-back is unable to sign for his new club with the Blues currently banned from offloading him.
Reports suggest the player will pen a new contract at Stamford Bridge to put Chelseain a strong negotiating position amid talk of a permanent move in the summer.
But Maatsen’s switch this month is on hold due to a little-known transfer rule.
Clubs are allowed to loan out up to seven players to foreign sides at one time.
Chelsea have already hit the maximum amount and they now must rip up a current deal to see Maatsen leave.
Romelu Lukaku, Kepa Arrizabalaga, Angelo Gabriel, Hakim Ziyech, David Datro Fofana, Gabriel Slonina and Diego Moriera are all on loan with clubs abroad.
There has been rumours that Ziyech could see his spell end with Galatasaray after struggling with injuries and form.
Meanwhile, Moriera has found it tough to get minutes at Lyon and is another recall option.
Speculation also suggests that Fofana may see his time end at Union Berlin – but he would then be sent back out on loan to Sevilla.
The maximum of seven foreign loans rule was put in place two years ago to stop teams stockpiling talent.
Players are exempt from the regulation if they are both club-trained, meaning they have spent at least three years in the club’s youth academy, and are aged under 21.
Maatsen is not spared from this rule because his 21st birthday came before the cut off at the end of last season.
Chelsea have already been busy in the loan market this January, sending Alex Matos to Huddersfield and recalling Andrey Santos from his season at Nottingham Forest.