Costa is expected to seal a £32 million switch to west London in the coming days having already completed his medical.
That leaves Atletico Madrid with a hole to fill in their front line, and it seems as though they are intent on using their good relationship with Chelsea - which has been fostered by Thibaut Courtois' three-season loan spell at the Vicente Calderon - to come to their rescue.
According to El Mundo Deportivo, the Spanish club are keen on completing a deal for Lukaku - who impressed while on loan at Everton last season - but will have to cough up €25 million for his services.
The big Belgian scored 15 times in the Premier League with the Toffees, but could still leave Chelsea despite their need for further reinforcements in attack.
Previous reports have suggested that he will indeed be allowed to leave Stamford Bridge this summer, with the likes of Tottenham and Borussia Dortmund also said to be monitoring his situation.
Chelsea are also looking to seal moves for Atletico pair Filipe Luis and Tiago, which could be announced in the coming days.