CHELSEA hired Gilbert Enoka to help create a winning culture at the club.
Enoka was the mental skills coach behind the "no d***heads" policy at the New Zealand national rugby team.
He has been working with the All Blacks for the past 22 years, with the last seven as the manager for leadership.
The 15 years before he took on that role, he worked as the team's mental skills coach.
Enoka will be taking up a "short-term consultancy role" with Chelsea.
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It will be his first job in football, but he is widely considered to have been an important part of the All Blacks' success over the last 20 years.
During his time with the side, he developed a culture that taught squad members to take responsibility for their actions.
The All Blacks stars would have to sweep changing rooms after games, and if one caused delays to the other players, they would have to explain it to them instead of the coaches.
His policy was often referred as the 'no d***heads policy', and speaking about it he said: "A d---head makes everything about them.
"Often teams put up with it because a player has so much talent.
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"We look for early warning signs and wean the big egos out pretty quickly.
"Our motto is, if you can't change the people, change the people."
Chelsea boss Graham Potter had to make a call of his Champions League squad last week, in which he dropped Pierre-Emerick Aubameyang from it.
While January signings Enzo Fernandez, Mykhailo Mudryk and loanee Joao Felix were added in.
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Reports have linked the Gabon striker with a move to the MLS, with Los Angeles FC being tipped with an interest.