Chelsea are prepared to go official to keep Diego Costa away from Atletico Madrid.

The Sun says the Blues have written a second complaint to the Spaniards, expressing fury at noises allegedly coming out of Madrid suggesting Costa is 'close' to re-signing for Diego Simeone's side.

A Chelsea source said: “We're writing to them again, a second time, but if this continues there are further options open to us, which includes reporting them to Fifa. We sincerely hope it does not go that far."

And Blues boss Antonio Conte called for Atletico to stay quiet over Costa.

Conte said: “It is normal to ask for respect.

“I don't know this situation but I know myself, my attitude and behaviour, that I don't like to speak about the players of other clubs.

“I'd like that others don't speak of the players of my team. I know this period is strange. We respect all — but we want respect."