Romelu Lukaku has not returned to Chelsea yet, because Diego Costa is refusing to join another club apart from Atletico Madrid.
Costa is adamant that he will not be pushed out the door by manager Antonio Conte, who has already told him to look for another club ahead of the new season.
The delay in offloading the Spain striker, is now complicating his efforts to land top target Romelu Lukaku from Everton, as his replacement.
It is understood that Costa has rejected a move to the Chinese Super League, as he holds out for a return to Atletico, who are banned from registering new players until January 2018.
Costa has two years left on his £150,000-a-week deal at Stamford Bridge.