Manchester City boss Pep Guardiola is "sad and disappointed" that Douglas Luiz will not be allowed to play this season after the 20-year-old Brazilian's work permit was rejected.
City reportedly sent the Football Association video footage supporting Luiz's application but to no avail.
The FA made their decision on Thursday, the day the transfer window shut.
"I accept the rules but it's difficult to understand. They don't know him," Guardiola said.
"They have to judge if he has the ability to decide. Me and [Brazil manager] Tite know more about it. They don't know him, not one game or training session," he added.
"We spent £12-£14m because he's a player with a huge capacity to play with us."
Brazil youth international midfielder Luiz, who joined City from Vasco da Gama in July 2017, spent last season on loan at Girona, which is part of the City Football Group.
He made 17 appearances for the Spanish club, but started only one league game.
FA rules on work permits were changed in 2015 "to ensure only the most talented non-EU players meet new criteria".
"I'm so sad and disappointed for Douglas, he could have played, he's shown many good things," Guardiola added.
"We are going to send him on loan again and try to get the work permit.
"I don't understand but we're in England and you have to accept it. I'd have preferred [to have found out] 10 or 15 days ago as we could have decided what we can do.
picaipry
0
see dis man. u were reluctant in adding to d squad bcos of Di's guy docglas now u see urself. u wanted to know 15 days ago.