Chelsea are exploring the possibility of signing Victor Osimhen on an initial loan from Napoli and are in talks with Atlético Madrid over the sale of Conor Gallagher.

Negotiations with Napoli over a deal for Osimhen that could take Romelu Lukaku to the Italian side on a three-year contract are understood to be ongoing, with the Nigeria striker believed to be keen on a move to Stamford Bridge. Paris Saint-Germain had been considered the frontrunners to sign the 25-year-old but have so far been unable to reach an agreement over a fee.

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Napoli’s president, Aurelio De Laurentiis, has set a release clause of about €130m (£110m) for Osimhen, who has been training separately from the rest of Antonio Conte’s squad and is yet to feature in their pre-season games. Chelsea sources have previously indicated they would not be willing to pay his release clause but they are believed to have raised the possibility of taking Osimhen on loan with an option to make the move permanent at the end of the season.

The future of Lukaku, who is due to return to training at Chelsea’s base in Cobham this week having spent two seasons on loan at Inter and Roma, could be crucial to striking a deal for Osimhen. The Belgium striker has two years of his contract remaining after re-signing for a club-record £97.5m in 2021 and has agreed personal terms with Napoli. Chelsea have previously held out for about £30m.

Chelsea are open to selling Gallagher to Atlético, who are understood to have proposed a package worth up to €40m (£33.7m) for the England midfielder. That is significantly below the £50m Chelsea had hoped to command earlier in the summer amid interest from Aston Villa and Tottenham, although the academy product now has less than a year on his contract.

It is unclear whether Gallagher would consider a move to Atlético but he is believed to be prepared to stay at Chelsea if the conditions for a move do not meet his requirements, raising the prospect of a departure from his boyhood club via a free transfer next summer.

Chelsea are trying to sell Trevoh Chalobah after leaving the defender out of their squad for the tour of the United States but are set to confirm the arrival of Filip Jorgensen after the goalkeeper completed his medical before a €24m (£20.2m) move from Villarreal.