Diego Costa was not on board his scheduled flight from Sao Paulo to London earlier this week, claim reports in Spain.
The Spain international has been in Brazil since June but was booked to return to Chelsea this week although now Marca report he never checked in for his flight.
It was expected the 28-year-old would make his first return to Stamford Bridge since last season and train with the club’s reserve side, with the anticipation of his sale to Atletico Madrid going through.
However, it now appears there has been yet another change of plans as the long-running saga shows no sign of slowing.
Reports in both Spain and England have suggested the two clubs are working on a deal close to €60m (£54m) but Atleti president Enrique Cerezo recently denied the club would negotiate for any player until January.