The Spanish striker has never been far from controversy but has put his disciplinary problems to one side to make Chelsea champions elect.
Costa has now been directly involved in 19 goals this season, after his fourth against Stoke his 14th strike this season with five assists, more than any other player in Europe’s top five divisions.
But after Chelsea took another step towards the Premier League title, Costa revealed just how close he came to leaving in the summer to former club Atletico Madrid and how his relationship with Italian Conte helped him stay at Stamford Bridge to such devastating effect.
“Could I have gone in the summer? Yes, yes. I was about to leave,” he said.
“I was about to but, well, I’m happy here as well and that’s that.
“Did I want to go? Yes. I had the possibility to go to Atletico, because of a few things, the family, the life I have there but not because of Chelsea, because, here, there’s a lot of love with the supporters, with the people, so I’m here very happy, I’m very content.
“People love me a lot. There was one thing I wanted to change for family reasons but, well, it wasn’t to be and I continue to be happy here.
“It was important too that the manager, from the very first minute, said he counted on me.
“The truth is the manager is good with the players, making more jokes with the players, and that’s good for us, to have a manager who is not just a boss but a person we can talk with, someone whose support we can count on in difficult moments.
“He is calm with the players and you can see the people love him more all the time.”
Certainly, Costa looks a far more mature player with just five yellow cards and no dismissals this term and he is starting to really bully defences demonstrated by his goal five minutes from time which sealed victory against a belligerent Stoke.
The West Londoners next face Tottenham on Wednesday, a fixture that caused such ill feeling last term that Costa clashed with Mousa Dembele. But the 28-year-old striker believes there will be no repeat of such scenes and you believe him.
“It’s a derby,” he said.
“It’s that. Both want to win. It’s a London derby, so the match is played a bit stronger but there’s no problem with it.
“We go there looking to do the best we can. I know what I have to do.
“I know when I do bad, so I thought about it and knew I had to improve that aspect because, here in the Premier League, the reality is there’s no mercy [authority], a lot of the time it seemed like they [referees] were against me.
“There was no other way, because if they’re not going to change, I had to change.”
This was not a comfortable afternoon for Chelsea with Stoke giving their hosts plenty of cause for concern.
Gary Cahill gave Conte’s side a 34th-minute lead when he headed in Cesc Fabregas’ concern but Stoke were level only seconds after the restart as Bruno Martins Indi volleyed home after Peter Crouch had caused a nuisance in the box.
Willian then converted from an Eden Hazard touch on 57 minutes but still Mark Hughes’ side refused to lie down with Crouch scoring from close range on 64 minutes.
Willian though fired home from Fabregas’ pass less than a minute later before Costa eased the nerves with a deserved goal.
Hughes was pleased with the performance of Crouch who threatened to upstage Costa at one point.
“There’s life in the old dog yet clearly,” the Stoke manager said.
“He’s 35 now. Peter’s got more game time left in him. I’ve been with him for four seasons, he hasn’t changed in terms of what he can offer and what he can produce.
“I don’t anticipate that changing in the next two or three years if I’m honest.”
Courtois 6; Azpilicueta 6, David Luiz 6, Cahill 7; Moses 7, Kante 7, Fabregas 8 (Matic 73, 6), Alonso 7; Willian 8, Diego Costa 8, Hazard 8.
Begovic, Zouma, Ivanovic, Chalobah, Loftus-Cheek, Batshuayi.
Grant 8; Johnson 6, Shawcross 6, Martins Indi 6; Diouf 6, Affelay 6 (Imbula 62, 6), Adam 7, Pieters 6; Allen 6, Shaqiri 7 (Bojan 61, 6); Crouch 8.
Given, Bardsley, Sobhi, Whelan, Bony.