The Brazilian-born Spanish international scored 36 goals in all competitions in the 2013/14 season, and as Jose Mourinho expressed his desire for a goalscoring striker to lead his attacking line, rumours of interest in Costa grew. A deal has been on the table since the end of the season, and with Spain's exit from the World Cup, any potential business can be wrapped up in the coming days.
The official statement reveals that Chelsea matched the release clause of the striker set by the Madrid-based club, and all that is left to be completed is an agreement of personal terms and a successful medical. With the 25-year old apparently desiring to join Chelsea - hinting at a move since the close of the season - personal terms should be agreed without much complication.
Costa's goalscoring record was better than the combined tally of all three of the Blues' strikers last season, who only managed 31 goals between them. Despite failing to impress in the World Cup, he has proven that he can score at the highest level in Atletico's run to the La Liga title and the Champions League Final.
The completion of Costa's signing will represent another step in Jose Mourinho's plan for Premier League domination. Cesc Fabregas has signed, and rumours of moves for Filipe Luis and Tiago are set to be completed. While fears of failing to comply with Financial Fair Play may haunt Blues fans, the sales of Juan Mata and David Luiz, and the departure of Frank Lampard and Ashley Cole, mean that the club is safely inside the allowed spending restrictions.
Chelsea fans have been excited at the prospect of securing the signing of Diego Costa since rumours of his arrival started circling in the media, and now Chelsea have officially announced that a deal has been agreed, they can be delighted that the club is doing all it can to continue the era of Premier League success at Stamford Bridge.