Revealed...
Costa sent a flippant reply and, according to Spanish newspaper AS, the next message from Conte read: 'Hi Diego, I hope you are well. Thank you for the season we spent together. Good luck for next year but you are not in my plans.'
The 28-year-old, Chelsea's top-scorer with 20 Premier League goals last season, is understood to have taken a screenshot of the conversation and forwarded it to team-mates and officials at the club.
Costa then ignored requests for him to calm down and leave the negotiations to the board, going public after Spain's 2-2 draw against Colombia on Wednesday when he revealed to the media how Conte told him he had no future at Stamford Bridge.
The whole unseemly episode does not help Chelsea as they attempt to sell Costa and boost the squad for a Champions League campaign.
AC Milan quickly emerged as a viable option but the Italians have told his representatives they are not prepared to match the £200,000-a-week wage demands.
Chelsea could try to strike a deal to subsidise Costa's salary as part of a loan package as they have in the past but Milan's new Chinese owners would not want their marquee signing to arrive on loan using them as a stepping stone to Atletico Madrid.
Costa has made it clear he would relish the chance to return to Atletico but his former club are banned by FIFA from signing players until the end of the year.
A big-money transfer to China was on the cards in January but interest has cooled and Costa will be aware of reports of the low standard of football in the Chinese Super League, where former Chelsea midfielders Oscar and Ramires are playing.
