Jose Mourinho "extremely confident" Chelsea will complete the signing of Atletico Madrid striker Diego Costa

The Chelsea coach believes that the Spain international will sign for the Blues after asking the club's hierarchy to sign him and insists Thibaut Courtois will be at Stamford Bridge next season

Diego Costa, who is currently at the World Cup with Spain, is reportedly on the verge of signing for Chelsea. (GETTY IMAGES)

Chelsea manager Jose Mourinho says he is "extremely confident" that the club will wrap up the signing of Atletico Madrid striker Diego Costa.

The Blues have long been admirers of the 25-year-old, who scored 27 goals in La Liga last season to help the Rojiblancos to their first league title since 1996, as well as eight goals in the run-up to the Champions League final.

And after allegedly agreeing to meet the £32 million release clause written into his contract, Costa was reported to have undergone a medical with the Blues before flying out with the Spain squad to the World Cup in Brazil.

Mourinho had previously been reluctant to discuss his interest in signing the Brazilian-born forward but has now revealed a deal is close to completion.

"Costa is a player I want in my team," he said in an interview with Marca.

"I've asked the club to bring him in and I am extremely confident that we are going to get him and he'll end up signing for Chelsea."

Meanwhile, Mourinho also dismissed speculation that young Belgian goalkeeper Thibaut Courtois could be sold this summer.

The 22-year-old has been on loan at Atletico Madrid for the past three seasons after signing from Genk for £6 million in 2011 and his reputation has grown significantly, winning the Zamora trophy for a second consecutive campaign after keeping the most clean sheets in La Liga last season.

He had previously been linked with a £20 million switch to Barcelona and Real Madrid as he has just two years remaining on his contract, but the Portuguese tactician insists Courtois is going nowhere.

He added: "When the World Cup in Brazil is over, Courtois will be coming straight back to Stamford Bridge - end of story".