The Spain international has bagged 32 goals in 54 appearances since signing for the west Londoners two summers ago, firing them to the 2014/15 Premier League title.
But multiple sources, including AS, claim the 27-year-old has struggled to settle at Stamford Bridge and wants to return to former club Atletico Madrid, where he lifted the La Liga crown in summer 2014.
Should Chelsea consequentially be forced to sell Costa this summer, it is claimed they’ll swoop for Napoli poacher Gonzalo Higuain as his replacement.
The Argentina international has just come to the end of his most formidable campaign to date, notching up 38 goals across all competitions.
The former Real Madrid ace has also refused to extend his Napoli contract past 2018, suggesting he could be on the move during the summer transfer window.
But the 28-year-old’s £78.7million release clause is still in place and AS suggest Chelsea may have to play it in full.