London: Claudio Ranieri's Leicester City were 5,000-1 outsiders to win the Premier League at the start of the season but, with 13 games left, they hold a five-point lead at the top of the table.
Ranieri is sparking a remarkable turnaround in Leicester's fortunes and Reuters has asked three players who worked under him during a previous Premier League stint at Chelsea from 2000-04 to offer an insight into the Italian coach's methods.
What was it like to work with Ranieri?
FORMER NETHERLANDS DEFENDER MARIO MELCHIOT (made 165 appearances for Chelsea between 1999-2004)
"A player's fitness is important to Ranieri because he wants to make sure you can handle the game at your best and that you can focus until the end.
"He hates players that get tired and make silly mistakes. He's a real winner. He'll make sure you know every game in training counts so you take the winning momentum into the game on a Saturday."
FORMER CAMEROON MIDFIELDER GEREMI (made 109 appearances for Chelsea between 2003-07)
"He was the manager who signed me. To work with him was a great experience, he was like a father to me.
"He was very demanding in training. He made sure he pushed us. He wasn't easy to work for.
"Footballers always complain when managers push them but it's important to work hard. When you train hard you are less exposed to injuries."
FORMER NETHERLANDS GOALKEEPER ED DE GOEY (made 179 appearances for Chelsea between 1997-2003)
"He is a typical Italian coach who likes a lot of physical work, work on team shape and long training sessions.
"A lot of things are down to power and you can see that in the way Leicester are playing, they run a lot, they work hard and that's what gets them results."
What are Ranieri's best qualities as a coach?
Melchiot: "He knows how to press opposition teams like no one else. You'll know how to defend as a team better than you knew before.
"Everyone needs to help everyone else, if not he'll take you out of the team."
Geremi: "He's one of the best managers. He likes discipline too.
"The players at Chelsea didn't like the way he rotated the team but the squad was big with a lot of good players. If you see the squad now at Leicester, it's not as good as our one was.
"He had to manage the situation at Chelsea, keep most of the players happy and keep getting results."
De Goey: "He can adapt very well to opponents. He knows all their strengths and weaknesses, that's one of his strong points, but the team meetings sometimes used to be quite long at Chelsea because his English wasn't the best then."
Are you surprised how well Ranieri has done at Leicester?
Melchiot: "Yes I am and I'm sure a lot of people are because last season Leicester just survived relegation."
Geremi: "Of course I'm surprised. Usually in the Premier League you know who is going to be in the top positions.
"I just want to say well done to Ranieri and his players. Their success is coming from the way the manager is educating the players."
De Goey: "Yes, I think everybody is, but I think the key point is everyone is working his socks off for each other for the whole match.
"They go quickly from defence to attack with players like Riyad Mahrez and Jamie Vardy up front."
Why do you think Ranieri is doing so well at Leicester?
Melchiot: "Deep down he wants to win the league badly and I'm sure the players know that too. But he won't let the media know it and that keeps the pressure off the players.
"In his last season at Chelsea we came second in the league. We were so close and I'm sure he doesn't want that to happen again."
Geremi: "At the start everyone said Leicester would get tired, they would start to lose, but they have an experienced manager who knows they have history to write.
"He won't panic in this situation, he'll know what to say, how to handle the squad. If he was a young manager he might be in trouble.
"I know he will be thinking of winning the league. They just have to believe they can win it."
De Goey: "Hard work is always the key to success. Nobody expected this from Leicester, they expected this from Chelsea, Arsenal, Manchester City, Manchester United, Tottenham Hotspur.
"Now we have to wait and see how far they can go. It could depend on injuries and suspensions because if anything happens to Mahrez and Vardy they will miss their quality."