Chelsea have reached an agreement to sign striker Diego Costa from Atletico Madrid.
The Spain international had long been linked with a move to Stamford Bridge.
Chelsea confirmed this afternoon that they had met the buy-out clause for the 25-year-old.
The transfer fee was not disclosed but Costa's buy-out clause at Atletico was about €40m.
"Chelsea Football Club can confirm an agreement has been reached with Atletico Madrid for the transfer of Diego Costa, with Chelsea meeting the buy-out clause for the Spanish international," read a statement on the club's official website.
Brazil-born Costa netted 35 goals for Atletico last season as they won the Spanish title and reached the Champions League final, where they lost in extra-time to Real Madrid.
The 25-year-old emerged as the leading summer transfer target for Blues manager Jose Mourinho, who was determined to add some firepower to a squad that came up just short behind Manchester City and Liverpool in the Barclays Premier League and were knocked out of Europe in the semi-finals by Atletico.
Atletico said Costa had sought a move to Chelsea but the club had insisted on receiving his full buy-out clause.
"Diego Costa communicated at the end of last season his will to be transferred to Chelsea and today the two clubs have reached an agreement for which the London club must pay the full amount set as the buy-out clause in the contract between the player and the club," it said.
Defender Ashley Cole has left Chelsea this summer at the end of his contract, along with England midfielder Frank Lampard.
However, former Arsenal captain Cesc Fabregas was signed from Barcelona on 12 June, the day before Spain crashed to a 5-1 defeat to The Netherlands in their opening World Cup match in Brazil.
Earlier, Chelsea announced goalkeeper Mark Schwarzer had signed a new one-year contract.
The former Australia international, 41, headed to Stamford Bridge last summer on a free transfer from west London neighbours Fulham to offer back-up to Petr Cech.
He went on to make 12 appearances, including the semi-final against Atletico after injury to the Chelsea number one.