Five flashpoints in Diego Costa and Antonio Conte's rocky relationship
This article first appeared on ESPN FC on Aug. 8, 2017.
Diego Costa's roller coaster three-year spell at Chelsea finally appears to be over after Atletico Madrid agreed a fee for him to return in January.
Antonio Conte had already informed him he is not wanted at Stamford Bridge and relations between the two men have been volatile from the start. Though Costa enjoyed the most prolific season of his Chelsea career in 2016-17 under Conte, scoring 20 Premier League goals for a title-winning team, there were hints throughout the campaign that things could end this way.
ESPN FC takes a look at the five flashpoints that have led Costa and Conte to a public and messy separation.
Costa tries to force Atletico return
Costa has never hidden the fact that he doesn't particularly like living in England and, given the choice, would quite like to go back to Atletico Madrid, where he first emerged as one of the world's most formidable strikers under Diego Simeone.
Last summer, with a disastrous campaign that cost Jose Mourinho his job at Chelsea fresh in the mind, Costa tried to take control of his destiny.
"On Conte's first day [at Chelsea], I told him that I wanted to join Atletico, and he was upset with me and didn't even look at me," Costa told El Larguero in March, adding, "I did all that I could to return [to Spain], but it didn't happen."
Chelsea's unwavering stance that Costa wasn't for sale eventually forced Atletico to turn to Kevin Gameiro from Sevilla. Meanwhile, Costa began the Premier League season on fire, scoring seven goals in his first seven games -- but the tone of his uneasy relationship with Conte had been set.
Conte refuses request to be substituted
Just as spectacular as Costa's goal scoring in the opening weeks of the season was his indiscipline. Four bookings in his first six Premier League appearances had the Spain international on the verge of suspension by the time Leicester City visited Stamford Bridge on Oct. 15.
Midway through the second half, with Chelsea ahead 3-0 and cruising toward victory, an agitated Costa clearly indicated to the Chelsea bench several times that he wanted to be substituted.
It was claimed afterward that he was worried about a fifth booking, while sources told ESPN FC that a small muscular injury was causing discomfort. His angry body language, however, suggested frustration at Conte's relentless instructions from the touchline.
In any case, Conte refused to indulge his striker. "I always take the responsibility in every situation, positive or negative," Chelsea's head coach said after the match. "Substitutions are always my decision."
A back injury and a bid from China
Chelsea led the Premier League by five points when news broke in January that Conte had dropped Costa for an away match against Leicester City after a furious training-ground row with a fitness coach over a back injury.
The argument occurred days after Chinese Super League club Tianjin Quanjian had offered to make Costa the world's highest-paid footballer, and Chelsea did not believe the timing was coincidental.
A 3-0 win at the King Power Stadium strengthened Conte's hand, and in his post-match news conference, well aware that feeding the Costa fire could derail Chelsea's charge to the Premier League title, Conte masterfully avoided closing the door on his striker's future at the club.
A truce was struck, and Conte quickly reintegrated Costa into his starting XI, but the episode strengthened the belief of many at Chelsea that the 28-year-old Costa's days at Stamford Bridge were numbered.
Batshuayi warm-up warning at the Britannia
Costa swiftly returned to the Chelsea team in body but looked a shadow of his 2016 self from mid-January to April, far less decisive in front of goal and increasingly willing to involve himself in petulant, physical battles.
In a fiery match against Stoke City at the Britannia Stadium on March 18, the striker was at his exasperating worst, tussling with several opposing defenders and earning a yellow card as early as the 17th minute.
Batshuayi has been sent to warm up very early by Conte, presumably as a warning to Costa to focus on the game #cfc- Liam Twomey (@liam_twomey) March 18, 2017
Conte immediately responded by sending Michy Batshuayi, a £33 million signing trusted with just 17 Premier League minutes in the previous three months, to do an extended warm-up on the touchline. It was an idle threat, but a threat nonetheless.
Career ended by text?
Conte's jovial public demeanour since arriving at Chelsea last July has for the most part concealed his ruthless streak, but Costa's mixed zone revelations after Spain's 2-2 draw with Colombia on Wednesday exposed just how uncompromising the Italian can be.
"I'm a Chelsea player, but they do not want me there," the 28-year-old told stunned journalists. "Antonio Conte has told me by message that I do not follow at Chelsea and that's it. Conte said he did not count on me for next season.
"It's a shame. I've already forwarded the message to Chelsea people to decide. But it is clear that the coach does not count on me and does not want me there. I have to find a team."
Costa also claimed that his relationship with Conte has been "bad" from the start, and while that appears a slight overstatement, it was clear that the unstable, at times explosive and often spectacularly productive partnership between the two men was set to end.
Liam is ESPN FC's Chelsea correspondent. Follow him on Twitter: @Liam_Twomey.