Chelsea
Diego Costa has scored three goals in his last two Chelsea appearances.AFP

Chelsea star Diego Costa wants Diego Simeone to guarantee him that he is going to remain as Atletico Madrid manager next season before forcing a potential exit from Stamford Bridge during the current transfer window, according to AS. The Spanish publication added that the deal is 'complicated' because the La Liga side would need first to cash in with Jackson Martinez to fund the move.

Costa, the Spanish international striker, has been linked with a return to the Vicente Calderon since earlier in the summer when Marca claimed that the striker was not happy with the London lifestyle. However, Atletico closed the door on him after turning their attention instead to Martinez, paying around £25.7 ($37.8m) to Porto to secure the services of the Colombian international.

But after both Martinez and Costa struggled in first part of the campaign speculation has increased in recent weeks.

The Spaniard himself hinted at that possibility following the Champions League win over Porto on 9 December, just games after former manager Jose Mourinho dropped him to the bench against Tottenham Hotspur and Bournemouth.

"You never know – look where Filipe Luis is now. Life is full of surprises," he said in an interview with Onda Cero. "I always wish Atletico the best and I always follow them, I support them from afar."

Atletico Madrid president Enrique Cerezo later refused to rule out his return too. Speaking to RTVE he said: : "Right now, Diego is a Chelsea player and he has to focus on Chelsea. But you never know what will happen in football and sometimes players do return to their former clubs."

Costa has rediscovered his goal form in recent weeks with three goals in his last two appearances. AS claims that Simeone has already spoken with the Spaniard to "persuade" him to go back to La Liga this window – having used the same methods in the past when he convinced Fernando Torres to move back to the Vicente Calderon.

The Spanish publication claims that "sources close to" Costa assures that the striker also wants to return but to "force his exit from Chelsea he wants Simeone to guarantee" him that he will remain at Atletico next campaign.

The deal, however, is "complicated" because Atletico would first need to find a new berth for Martinez, who during the summer transfer window was heavily linked with some Premier League clubs, including Liverpool and Arsenal.