Romelu Lukaku's return to Stamford Bridge doesn't appear to be a happy one.

The Belgium striker admits that he's unhappy with the system manager Thomas Tuchel has employed with the Blues.

"Physically, I am fine," Lukaku told Sky Sports. "But I'm not happy with the situation at Chelsea. Tuchel has chosen to play with another system - I won't give up, I'll be professional. I am not happy with the situation, but I am professional - and I can't give up now."

Lukaku, 28, scored the Blues' lone goal in a 1-1 draw with Brighton on Wednesday. It was his fifth goal in 13 league appearances this season.

A native of Antwerp, Lukaku rejoined Chelsea in the summer in a club-record £97.5 million transfer from Inter. In his two seasons with the Nerazzurri, Lukaku scored 47 goals in 72 league matches.

He says that he regrets the manner in which he left Inter last summer and hopes to return the club one day.

"I really hope from the bottom of my heart to return to Inter not at the end of my career, but when I'm still at [a] top level to win more together," Lukaku said. "I want to apologize to the Inter fans, [the] timing of my words was wrong: what you did for me will remain forever."

Lukaku had previously been on the Chelsea books from 2011 to 2014, but only made 10 league appearances, having spent time on loan with West Brom and Everton.

Having also played for Manchester United, Lukaku's 118 career Premier League goals are 20th-most all-time and third among active players behind only Harry Kane (170) and Jamie Vardy (127).