Mourinho is famed for his man-management skills and established a siege mentality during his first spell at Stamford Bridge which saw everyone buying into his philosophy and pulling in the same direction.

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The Portuguese was able to return the Premier League title to west London after being reappointed, but saw things turn sour in 2015-16 as both he and Chelsea endured a humbling fall from grace.

Costa concedes that the now-Manchester United boss cannot shoulder all of the blame for that slump, but acknowledges that performances and results are easier to come by in a happy camp – with Conte having brought a family feel back to the club.

He told Chelsea TV: “I think it’s really important for managers to be liked by his players because ultimately on the pitch, those players will give everything for their manager.

“We have had a change of manager, he is working us hard, but people like him, which is important for everyone connected to the club because it creates a good atmosphere. Sometimes you have managers that have to be the boss, but this manager is a bit friendlier and there is closeness there.

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“It is really important to have that at your workplace for you to come in and feel happy. You need a good atmosphere and a bit of fun.

“When a game comes around, that’s the time to be serious. During the week the training sessions are serious, but away from there, you have to relax and switch off.

“We are a family, we spend so much time together, we have to do things that bring us closer together because if not, everything will be too regimented, too professional and I don’t like that, it’s not for me.”

On Mourinho and the changes made by the current regime which have delivered a 13-game winning run and a standing five points clear at the top of the Premier League table, Costa added: “We had a great manager in Mourinho, who gave us a lot in that first season [Costa’s first at the club]. But last season, things just didn’t go well for us.

“We knew we had to change things, it wasn’t just the manager’s fault. We had to put in that bit more too.

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“Also in terms of change, it has been a bit of everything: a new manager and wanting to win things because when you do, it’s wonderful and losing hurts.

“We have the backroom staff that he brought too and they have contributed to the good atmosphere, so the manager is great and we are all behind him.

“We have got to know him properly now and while at first some people might not have liked some of the changes, now he is getting results and convincing people.”