Chelsea are keen to tie up a deal for Atletico Madrid striker Diego Costa before the World Cup, Press Association Sport has learned.

The club have tabled a formal bid for the Spain striker, whose 36 goals helped fire Atletico to the La Liga title and take them into the final of the Champions League, where they were beaten in extra-time by city rivals Real.

The Brazil-born forward, 25, is reportedly keen to move to Stamford Bridge, with Chelsea looking to push through a deal, believed to be around £32m, as quickly as possible.

"Chelsea have made an offer to Atletico Madrid in compliance with the buyout terms in Diego Costa's contract, and have been advised that the player has provided notice to Atletico Madrid invoking the buyout clause and directing the club to accept Chelsea's offer," a club source confirmed to Press Association Sport.

"Chelsea look forward to entering into formal transfer documentation with Atletico Madrid as soon as possible so that the player can concentrate on the World Cup."

Blues boss Jose Mourinho is keen to bolster his squad next season, having finished third behind Manchester City and Liverpool, while being beaten in the semi-finals of the Champions League by Atletico.

"I think it looks like he's really interested in leaving Barcelona, and is very, very interested in coming back to England" - Jose Mourinho on Cesc Fabregas

Mourinho confirmed he was interested in bringing Cesc Fabregas to Chelsea, with the midfielder seemingly on the brink of leaving Barcelona.

Arsenal have an option to buy back the Spaniard as part of the deal that took him to the Nou Camp in 2011 but currently appear unlikely to do so, leaving the door open for their London rivals to move for the 27-year-old.

And while Blues boss Mourinho did not confirm that a bid was imminent, he did admit that he was monitoring the situation closely.

"We have some interest," Mourinho told several UK national newspapers. "We have some interest. I have interest in analysing the situation.

"I think it looks like he's really interested in leaving Barcelona, and is very, very interested in coming back to England. This I think is clear.

"After that it's not something for us, or another team, for now. It's not for now, or tomorrow, or for before the World Cup.

"There is a process where he wants to leave, he wants to come to England because it's the country where he wants to be, where he prefers to play.

"We are interested in monitoring the situation."

If Fabregas were to arrive at Stamford Bridge, it would likely be as a replacement for Frank Lampard who announced last week he would not be returning this summer after 13 years and 211 goals in west London.

The 35-year-old was a lynchpin during Mourinho's first spell in charge at the club and the Portuguese insists the door is always open for the England international to return in some capacity.

"It's not the end of Frank's career at Chelsea - it's just a little break," he said.

"It's the end of his career as a Chelsea player, but he will be back for many, many years because he's one of the most important players in the club's history.

"You can't imagine how difficult it was for him to leave."