LONDON -- Diego Costa says his close relationship with Antonio Conte has been a key factor in his spectacular form for Chelsea this season, after a summer that almost saw him return to Atletico Madrid.

A record-equalling run of 13 consecutive Premier League victories has lifted Chelsea six points clear at the top of the table at the halfway stage of the campaign, and Costa has been the Blues' biggest driving force on the pitch.

The Spain international returned from suspension to score his 14th goal in 18 Premier League appearances during Saturday's 4-2 win over Stoke City at Stamford Bridge, while he has also registered five assists this season.

Speaking after the match, Costa revealed that Conte has utterly transformed the atmosphere around a club that was in disarray only a year ago, when Jose Mourinho was sacked for the second time with Chelsea languishing in 16th amid "palpable discord" between players and management.

"The team has changed, not just me," Costa insisted. "I think last season, we felt frustration. We didn't give the account of ourselves we should have done. We weren't the team we should be. I wasn't the player I should be, with an injury, so there were various issues.

"But I believe this season it has changed. The manager has come, and he's applied his ideas, and things are going well.

"The manager is good with the players, every time making more jokes with us. It's good for us to have a manager who is not just a boss but like 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."

Costa's form regained a measure of respectability in the second half of last season but in the summer his preference was to leave Chelsea to go back to Atletico, where he first made his breakthrough at the top level under Diego Simeone.

Diego Costa has scored 14 goals in 18 Premier League matches this season. Adam Davy PA Wire/PA Images

Atletico's public pursuit of Costa riled Chelsea, who never wavered in their determination to keep their star striker, and the 28-year-old insists his wish to return to Spain did not mean he was ever unhappy with life at Stamford Bridge.

"Yes, I was about to leave. I was about to... but, well, I'm happy here as well and that's that," he added.

"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. Here there's a lot of love with the supporters, with the people, so I'm here very happy, I'm very content.

"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."

One of the more striking aspects of Costa's form this season has been his improved discipline. After picking up four yellow cards in his first six Premier League matches, he went 10 games without attracting punishment from officials, despite being one of the most fouled players in the division.

Conte has frequently praised Costa for "showing his passion in the right way" this season, and the striker says he has adapted his approach based on his perception of referees in England.

Asked if Conte had told him to rein himself in on the pitch, Costa replied: "No, no. 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.

"A lot of the time it seemed like they [the referees] were against me. There was no other way, because if they're not going to change, I had to change."