“Liverpool were quickest off the mark, offering €25m (£17m) for the Brazilian and triggering the release clause in his contract. However, Jose Mourinho, recently returned to Chelsea, had also identified Costa as a primary target, a Didier Drogba-style centre-forward around whom he could forge a new winning machine. The Portuguese coach had watched Costa since he first arrived at Braga, and had felt the force of the striker during his breakout season close-up as manager of Real Madrid.”
“However, Mourinho had yet to persuade the owner of Chelsea, Roman Abramovich, to accelerate his rebuilding plans. In both acquiring new players and moving others on, the process would be gradual. For example, Benfica’s Nemanja Matic, another immediate target for the new manager, would have to wait until January 2014.”
“If Costa could not be signed now, a strategy was needed to ensure he was delayed, and not diverted. Chelsea and Mourinho made their case to Costa and Atletico: turn down Liverpool now and we will sign you – for more money – in 12 months.”
“Samuel Eto’o was the stop-gap acquisition. Behind the scenes, Costa was lined up for summer 2014, in negotiations aimed at making all parties happy for the season ahead. On August 14, the club renewed Costa’s contract, doubling the salary and extending until June 2018. The release clause also went up, and the understanding was that the new season would be Costa’s last for Los Colchoneros.