The Chelsea boss has refused to confirm that his side have agreed a deal to bring the Brazil-born Spaniard to Stamford Bridge in a £35 million deal this summer
Chelsea manager Jose Mourinho admits signing a striker is "critical" but is refusing to say whether the club will move for Diego Costa this summer.
Goal revealed on Friday that the Blues have agreed a £35 million deal to bring the Brazil-born Spaniard to Stamford Bridge, with the deal to be confirmed before the World Cup.
Mourinho was unwilling to say publicly whether Costa - who has scored 27 goals in La Liga this season - was the man his team were chasing but reiterated that a new striker was much-needed.
"We are not going to be buying and selling and selling and buying," Mourinho told reporters.
"We're going to do a couple of critical signings. Is a striker a target for us? Yes, we've never denied that.
"Diego Costa is a good player but he's an Atletico Madrid player so I cannot say much."
Mourinho gave even less in regards to the future of goalkeeper Thibaut Courtois, who is in his third season on loan at Atletico but owned by Chelsea.
"I prefer to say that he is Atletico Madrid's goalkeeper. I prefer to call him that," he added.