The Portuguese midfielder has spoken out about on the controversial summer transfer from Sporting Club to Leicester City on the last day of the transfer market.
His registration took place 14 seconds after deadline and, despite appeals, FIFA ruled that Adrien had to stay in a state of limbo until January when he will finally be allowed to play again, albeit not in the Foxes New Year's Day clash with Huddersfield because he can't be registered the day before the game.
"I cannot hide that it was a big disappointment, a lot of the negotiations were made in the nick of time," he told RTP.
The 28-year-old also reinforced his passion for Sporting and admitted he has already noticed the difference in his new club's goals compared to his former employers.
"The first goal is not to be a champion, that's the difference I found from Sporting to Leicester," he added. "Sporting will always be my home, I'm going to get stronger from this situation, I have no doubts."