The 27-year-old joined the Blues from the La Liga giants during the summer of 2014 and quickly settled in west London as he helped to fire the club to title glory last term.
However, this season has been far less fruitful for the combative Spaniard, who has notched just three goals in league action and fallen with manager Jose Mourinho after being dropped for Sunday’s 0-0 draw against Spurs.
His actions – he threw his training bib towards his manager in a fit of rage from the bench – appears to have called his Stamford Bridge future into question, and reports claim that Atletico are considering a £28m offer for their ex-marksman.
Costa is still considered to be a hero among Rojiblancos fans after he netted in excess of 30 goals to help Atleti to the league title and Champions League Final in 2013/14.
It’s understood that there is a clause in place for the Madrid side to lure him back for £28m.