Manchester United manager Erik ten Hag called for a change to profit and sustainability rules on Friday as Scott McTominay is set to seal a move to Italian side Napoli.
A product of the United academy, McTominay's departure will allow the Red Devils to further strengthen their squad before the transfer deadline with Uruguayan international Manuel Ugarte expected to join from Paris Saint-Germain.
The sale of players who came through the youth system is particularly helpful for clubs to comply with financial regulations as the full transfer fee is recorded as a profit in the books.
Profit and sustainability rules that limit Premier League clubs to losses of £105 million ($138 million) across a three-year assessment period have been blamed for a quiet summer transfer window.
"I would prefer not to lose him because he's Manchester United in everything," Ten Hag said at his pre-match press conference ahead of Sunday's clash with Liverpool.
"He was so important for our team, for Manchester United, but unfortunately it's the rules.
"We have to discuss the rules, when you have to sell and obviously homegrown and academy players bring more value, that's not the right thing to do.
"But I think for everyone, for all parts it's a good deal, for Scott he's happy with it, for Napoli a very good player, but also for us."
There could be more comings and goings at Old Trafford before the 2200GMT deadline.
Jadon Sancho has been linked with Chelsea, raising the possibility that outcast Blues winger Raheem Sterling could move to United in return.
United have already spent around £150 million during the window on Leny Yoro, Matthijs de Ligt, Noussair Mazraoui and Joshua Zirkzee.
“We have a couple of conversations going on at the moment. That’s all I can say. We’ll see what happens," said United's sporting director Dan Ashworth after attending the Europa League draw in Monaco.
"There’s still a few hours to go, who knows what will happen in the last few hours. But we’ve been really pleased with the business we have done, in and out."