Antonio Conte’s decision to dump his top scorer by text — and Diego Costa’s reaction to go public on the private exchange — has stunned the Chelsea board and is set to cost them millions.

It is hard to envisage a way back at Stamford Bridge for Costa after this latest episode in a stormy relationship with Conte. The manager’s own rogue activities will certainly damage his club’s negotiating stance.

Would-be buyers now know Chelsea are desperate to sell, as do those who might sell the Premier League champions a replacement — such as Everton, who are less likely than ever to reduce their £100million valuation of Romelu Lukaku.

Antonio Conte informed Diego Costa of his decision to axe him from his plans by text message

The Italian manager's own rogue activities will damage his club's negotiating stance

Conte's unofficial text message also opens the way for Costa’s agent to demand a hefty loyalty payment, with clear proof the club have instigated his exit.

While on holiday, Chelsea’s manager sent a goodwill message to all his first-team players wishing them a happy time with their families and reminding them to do some physical activity and stay in shape.

Costa fired off a reply, not thought to have been openly provocative but enough to irritate Conte. The Italian sent back a message which left his striker in no doubt that he is no longer part of his plans.

Costa reported the text exchange to the club and he received a message relayed back from director and chief transfer negotiator Marina Granovskaia telling him to back off and leave the negotiations to her.

On Wednesday, after he was an unused substitute in Spain’s 2-2 draw with Colombia, Costa came out of the dressing room and revealed all to the Spanish media about his ‘bad’ relationship with Conte.

The Spain international told media that he was looking to leave Chelsea after the exchange

Costa came out of the dressing rooms on Wednesday and revealed all to the Spanish media

DIEGO COSTA IN 16-17 Appearances: 35 Goals: 20 Shooting accuracy: 38 per cent Assists: 7 Passes per match: 29.54 Big chances created: 6 Big chances missed: 12 Premier League stats only Advertisement

The striker said: ‘The other day, Conte sent me a message saying he does not count on me for next season. So I’ll have to find a way out. If the manager gets in contact to tell you that you are not wanted then you have to leave.’

He reaffirmed his love for Atletico Madrid and of life in the Spanish capital but knows his former club are banned from signing players until the end of the year. AC Milan have emerged as a genuine alternative.

Chelsea have been working hard to strengthen the squad in preparation for a return to the Champions League. They have looked at Tiemoue Bakayoko of Monaco and are considering another move for Virgil van Dijk after Liverpool dropped interest in the Southampton centre half following accusations of an illegal approach.

Lukaku wants to return to Stamford Bridge but the clubs are not close to an agreement on the fee. And the revelations making it clear Costa is on his way out do not help the champions.

Club director Marina Granovskaia told Costa to back off from transfer talk after the argument

Costa's relationship with Conte has been fractious since Chelsea's summer tour of the USA

COSTA AT CHELSEA 2014-15: 21 goals (0.6 goals per game) 2015-16: 16 goals (0.4 goals per game) 2016-17: 22 goals (0.5 goals per game) Total goals: 59 Advertisement

Costa’s relationship with Conte has been fractious from the start.

Problems were brewing from the sunny California days of pre-season when Costa claimed a bad back prevented him from taking part in the long, pattern-of-play exercises and was duly dropped from friendlies against Liverpool and Real Madrid.

Conte made it clear he would not select any player unable to take full part in his training sessions.

There were eruptions during the season. Conte was unhappy with petulant acts of rebellion such as a training ground dispute with a fitness coach and an angry gesture asking to be substituted during a home game against Leicester. Then there was a video posted on social media of him drinking a bottle of beer in the dressing room and threats to let off a fire extinguisher as Conte addressed the media having won the title at West Brom.

Conte and Costa fell out after the striker continued with petulant acts of rebellion

Costa was caught drinking a beer in the Chelsea changing room following a victory

Costa and David Luiz interrupted Conte's press conference at West Brom

He was also pictured in the press-room buffet at half-time during the victory over Watford

There was a half-time visit to the press room buffet by Costa during the penultimate game of the season, against Watford.

This was caught on camera and circulated on social media during the second half.

The relationship was held together for the sake of the team and the title bid, often with Conte making light of the events in public. He needed Costa up front and the striker ended the season with 20 goals in the Premier League. Privately, however, Conte resolved to find a replacement.

Chelsea hoped a mega-money offer for Costa might emerge from China to help fund a recruitment drive. Tianjin Quanjian showed interest in January amid reports they were prepared to pay £72m, but the route to the Far East has since gone cold.

This brings the fee down into the realms of what top European clubs might pay for an unwanted 28-year-old with only two years left on his contract. Costa made it clear after the FA Cup final that he was unhappy with the feeling he was being forced out and stated categorically he would only sign for his former club Atletico Madrid.

Atletico, however, are banned by FIFA from signing players until the end of the year.

AC Milan are in the market for a striker and Costa’s agent Jorge Mendes spoke to Milan directors Marco Fassone and Massimiliano Mirabelli in Cardiff prior to the Champions League final.

The Brazil-born striker has been clear that he wants to return to former side Atletico Madrid

Costa's demand for a transfer may be scuppered by the signing ban hanging over Atletico