Diego Costa will definitely be playing at Chelsea next season, a situation that has been on the cards since he signed over all decision making power to his agent Jorge Mendes.

The Portuguese super agent made an agreement some time ago with the London club that included a penalty clause whereby the player would have to pay out several million Euros if he turned his back on the deal.

Despite that, Costa was said to have thought about it on a number of occasions and discussed with his closest friends the possibility of staying at Atlético for another year. The club even made an improved offer on his current deal to sway his decision to stay in the Spanish capital and it nearly worked.

However, it was the contract signed by Mendes that made it inconceivable that Costa would continue under the orders of Diego Pablo Simeone next season. The amount of money Costa would have had to pay to do that put the blockers on that plan and in the last few weeks of the season the player began to get used to the idea that Stamford Bridge will be his next destination.

What helped Costa to dispel any doubts he may have had was the confidence José Mourinho has shown in signing him, as well as the fact that some of his best friends at Atlético, Filipe Luis and especially Tiago Mendes, will be joining him.

Tiago will return to Chelsea firstly because he is a quality player, but also because Mourinho specifically requested that he sign with the Blues so that he could help Costa with the adaptation to a new country and league.