Lukaku was re-signed by the Blues back in 2021 in a club-record transfer worth £97.5m, but struggled to break into Thomas Tuchel's side in 2022 and was not included in Mauricio Pochettino's plans the following year either.
The 31-year-old, who still has two years left on his contract at Stamford Bridge, has spent the last two seasons on loan in Serie A with Inter Milan and Roma.
Despite Daniele de Rossi's side having a largely disappointing domestic season in 2023-24, the Belgian international had a decent campaign, netting 13 goals and three assists in 32 league appearances.
However, his performances in Europe were significantly better, where he managed to record a total of seven goals and an assist in 13 Europa League games.
Lukaku returns to West London but his future remains unclear
While he has delivered solid numbers in Italy over the last two terms, Lukaku has not managed to seal a permanent move to Serie A, mainly due to his substantial price tag.
After departing Roma at the end of last season, the Daily Mail now report that the Belgian is set to return to West London in the coming days, though his future remains unclear.
The report adds that while Lukaku will recommence training at Cobham, he will be doing so with players whom the Blues are looking to part ways with this summer.
Most of the Chelsea squad are currently in the USA for their pre-season tour, participating in several friendly matches as they gear up for the new Premier League season, which starts in less than three weeks.
However, the club have opted to keep behind a select group that are expected to either be loaned out or moved on permanently this summer.
Among those who have remained in West London is Trevor Chalobah, who is believed to be one of the most likely players to be sold in the current transfer window.
Having come through the Blues' academy, selling the 25-year-old would represent pure profit for the club, and will help them maintain compliance with the league's Profit and Sustainability Rules.
Conte considering Lukaku as Osimhen replacement?
Sky Sports Italy suggest that Lukaku's time at Chelsea is close to coming to an end, with Napoli boss Antonio Conte reportedly making the signing of the Belgian one of his top priorities ahead of the new season.
It is understood that Lukaku has already been approached by the former Chelsea manager about a permanent switch with the possibility of a three-year contract.
The Blues are asking for £30m plus add-ons for the Belgian international, but Napoli are believed to be unable to finalise a deal until they can confirm a sale for Victor Osimhen.
Paris Saint-Germain are said to have engaged in discussions with Napoli regarding Osimhen, but the Serie A club is hesitant to accept an offer below his £110.8m release clause, which is a valuation that discouraged both Chelsea and Arsenal from pursuing a deal.
The Ligue 1 champions are reportedly considering a bid that includes £84.3m upfront along with a player as part of their offer.