Romelu Lukaku said he is unhappy with manager Thomas Tuchel's system while also admitting he would like to return to Serie A side Inter Milan in the future.
Lukaku left Inter for a return to Chelsea in August on a $131 million transfer.
"After two years in Italy, in which I worked a lot at Inter with trainers and nutritionists, I am physically fine. But I'm not happy with the situation, this is normal," Lukaku told Sky Italy.
"I think the coach has chosen to play with another system, I just have to not give up and continue to work and be a professional. I am not happy with the situation, but I am a worker and I must not give up."
Sky did not say when the interview took place and did not elaborate on the "situation," with the full interview set to air on Friday.