Brendan Rodgers has outlined the two key factors he believes enabled Jamie Carragher to enjoy a glittering 16-year career at the highest level for Liverpool – desire and fear.

The 35-year-old will hang up his boots following Sunday's clash with Queens Park Rangers in what will be his 737th and final appearance for the Reds.

Rodgers may have only had less than a year of working with Carragher, but the defender's qualities, determination and hunger have certainly made a lasting impression on the manager.

Asked what he believed had been the elements in allowing Carra to sustain such high performance levels for the duration of his career, Rodgers told Liverpoolfc.com: "It's probably a mixture of desire and fear.

"When I think about him, I think of trying to be the best you can be. There's that mixture and desire of wanting to be the very best.

"But I believe there's also a fear. Not a negative fear - a positive fear - in there that somebody wants to take your shirt.

"That combination always drives you on to be the best you can be."

In addition to the mental aspects of Carragher's game, Rodgers feels the Scouser's technical attributes are deserving of greater praise.

Indeed, the Liverpool manager feels the legendary No.23 elevated himself to 'world-class' status over the last decade and a half.

"It's not just one element," said Rodgers. "What makes you world class is more than one ingredient. He truly was a world-class operator. He went thought a period where he was up there in the top two to three centre-backs in world football.

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"His level hasn't dropped off too much, I've got to be honest. I can count on one hand the amount of mistakes he's made in training and in games - he's been phenomenal.

"When you play at that level and to the level he has, you've got to be mentally tough and you've got to have mental fitness. There's certainly no-one better in the game mentally than him.

"Physically his body has changed over that, that's what happens, but he's dealt with those changes and still kept the professionalism in his diet, nutrition and preparation.

"Tactically, he's probably developed so much over the course of his career from playing with top players, playing against top teams and learning different aspects from different managers.

"The one area that never really gets mentioned for me about Carra is his technique. When I came into here, everyone had talked about his mental fitness and those qualities, but I've been blown away by his technical quality.

"He can play any pass - left foot, right foot - his heading ability, his ability to time tackles and read the game. His technique is right up there and the mixture of all of those things has made Jamie Carragher world class."

Rodgers and Carragher locked in deep conversation are images that have been captured by both our photographers and LFC TV cameras during numerous training sessions at Melwood over the course of the last season.

So just what have the pair been chatting about so extensively?

"We've had both kinds of chats, really - football and life," Rodgers revealed. "I like to communicate with my players, and hopefully he's enjoyed the conversations as much as I have.

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"He's a real bright guy and I think the viewers when he moves into TV and punditry next season will really get a grasp of his intelligence and how articulate he is as a man.

"I have had good, thought-provoking conversations with Jamie and hopefully he has felt that as well. It's been one where the relationship has been strong and always open. He's a good guy."

Carragher's retirement presents Rodgers with the conundrum of how to replace a player of his quality and experience at the heart of his defence.

"I don't think there's many of Jamie - if any - around," considered Rodgers. "I don't think there is that type of player. He is an experienced player with great values and ethics.

"We have to hunt high and low to try and bring in a different type of someone - or maybe a few players - that is going to help us overcome that loss, because there is no doubt a man of that calibre leaving our group is a loss.

"But football has shown over time that for the greatest players like Jamie, time catches up with us all. The game moves on and we'll look at getting other people in to do a different type of job that can hopefully compliment the group."

So, with his distinguished playing career now at an end and a stint as a Sky Sports pundit to follow, does Rodgers foresee a time when Carragher and Liverpool FC are reunited?

He stated: "I believe so. But he's had 20-odd years of preparing his body and mind to play at the elite level.

"When you play 737 games for the football club, that takes a toll on you and you need to have a breather - you need to go away and have a period of time to relax and re-focus again.

"There's no doubt the door will always be open for Jamie here and if ever he decides to go down that coaching route, I would only be too glad to have someone like that stood beside me."

A new documentary featuring Jamie Carragher's managers, teammates and some high-profile opponents airs for  the first time at 7pm BST on Friday, May 24 on LFC TV. 'Carragher' will also be available on LFC TV Online and will conclude a fortnight of tributes across club media.