The Blues are currently undergoing a re-shuffle under manager Antonio Conte, who has been tasked with ensuring the Blues’ midtable finish last term was a mere blip.
N’Golo Kante and Michy Batshuayi have already been signed for a combined sum of just over £60m, but reports suggest that the London club are not done yet, with Lukaku on their radar.
The 23-year-old famously left Chelsea in 2014 after a series of loan moves.
It has since emerged that he is keen on the idea of heading back to Stamford Bridge, where he has ‘unfinished business’, and it’s claimed that if he does, Costa will be granted permission to re-join Atletico.
The Spaniard has been linked with a move back to the Madrid club he left two years ago for Chelsea, with the La Liga heavyweights having made him their top target this summer.