Leicester City manager Claudio Ranieri is an "amazing man" but a "hard coach", according to Marcel Desailly.
Desailly played under Ranieri at Chelsea between 2000 and 2004, a spell in which they finished second to Arsenal's 'Invincibles', who won the 2003-04 Premier League title without tasting defeat.
The Italian has a reputation for a light-hearted personality and is credited with garnering fantastic team spirit at the King Power Stadium.
However, World Cup-winner Desailly insists Ranieri has a tough side to him when it comes to dealing with players on a regular basis.
"He's not an easy coach, Claudio. If the players behave correctly, fine, otherwise he's ready for the fight," said Desailly.
"He doesn't care who is who, he will be on your shoulder. He's a strong man.
"In life he's an amazing man, but as a coach he's hard. I was captain at the time at Chelsea so I had some good meetings [with him]."
Having struggled to accumulate major honours during his career, Desailly is delighted to see Ranieri on the brink of success with three more wins required to secure Leicester the Premier League title.
"I'm happy for him with this end of career, because he's not going to coach for the next 10 years," he said.
"He's not been a winning coach. [In] 2004 we were supposed to win the league, but unfortunately Arsenal were 'The Invincibles' and he got sacked while he was building something good.
"You can see from how he talks he's calm, but I'm happy at least to get Leicester to the Champions League qualifiers.
"Now we are all expecting to see when is going to be the announcement that Leicester, like Blackburn, have won the Premier League, because we are tired of it being the same."
The former France international thinks Leicester's success is good for the Premier League as a whole.
"I'm surprised. It's good because it's proved that some of the clubs have invested correctly on players and it has lifted the level of the Premier League," added Desailly.
"Even if there aren't many in the finals of the Champions League, we are happy about how it has brought some curiosity. Even if you don't have individually top-class players, they've been able to stick together until the end."
