Andy Murray says he could not turn down the "unique opportunity" to coach his long-time rival Novak Djokovic at the upcoming Australian Open.

Speaking for the first time about the partnership, Murray revealed he had the unexpected conversation with Djokovic during a phone call in his car - shortly after telling a golfing partner he had no desire to move into coaching yet.

The 37-year-old Briton only retired from playing professionally in August.

After discussing the proposal with his family, Murray agreed to help Djokovic on a trial basis in Melbourne.

Serbia's Djokovic is aiming to win a record-extending 11th Australian Open title, as well as a 25th major which would put him clear of Australia's Margaret Court in terms of all-time victories.

"[Novak] asked if I would be interested in helping, which I obviously wasn't expecting," said Murray.

"I said to him: 'Look, I need to think about it and talk to my family.'

"So I spoke to them, and after a couple of days, I thought that it was a pretty unique opportunity and experience.

"I thought it would be a good idea to try it."

'It's not laughs and jokes' - how the early days have looked

If it had been suggested to Murray in Paris that he would be back in the game and coaching Djokovic five months later, you imagine he would have laughed.

There will be little, if any, japing around in Melbourne.

The pair are born winners who know the dedication and commitment required to be the best.

From the glimpses this week, it is clear anything less than Djokovic landing a record-extending 11th title would be unsatisfactory.

"At times it's very enjoyable. But high performance is not supposed to be laughs and jokes and messing around," said Murray.

"In all the times I've been on tour, I haven't seen that from any of the best players in the world.

"I've seen it from some of the lower ranked players, and that's one of the reasons why they're not there."

During Djokovic's open practice sessions against Carlos Alcaraz, Jack Draper and Arthur Fils on Rod Laver Arena, Murray watched every movement intently.

Stood close behind Djokovic and sometimes in the doubles alley, Murray constantly offered feedback, shouted praise after winners and made notes during the practice sets.

He also compared observations with Boris Bosnjakovic, who ran Djokovic's training centre in Belgrade before becoming part of the team last May after long-term coach Goran Ivanisevic left.

"It's about making small changes to things and trying to help him and improve with the whole team," said Murray.

And what about when things aren't going so well? Murray and Djokovic are both known for sounding off at their box, but this time the Scot might find himself on the receiving end.

"I know it's not easy out there - it's stressful and at times he's going to want to vent towards his team and his box," said Murray.

"Providing that he's giving his best effort and trying as hard as he can, I'm absolutely fine with him expressing himself how he wants."

'I was playing golf and then Novak messaged me'

Three-time Grand Slam champion Murray ended his career - where he regularly battled with Djokovic - at the Paris Olympics.

In the following months, he spent more time at home with his wife Kim and their four children, while also honing his skills on the golf course.

The surprise announcement in November that he was linking up with Djokovic, who he first met when they were 12-year-olds playing junior tournaments, sent shockwaves through the tennis world.

"I was playing golf, and we'd been exchanging messages. Novak had messaged me, just wanting to chat," Murray explained further.

"Then I was on the 17th hole of the golf course and the guy I was playing with said: 'Do you know what's next?'. I was like: 'No, not really'.

"He said: 'Do you have any plans to do any coaching?' And I said, 'Honestly, I can't think of anything worse to do right now'.

"Then 30 minutes later, I was in the car and called Novak, and we had a conversation."

Murray, who said his wife Kim was "very supportive" of the idea, has not ruled out coaching Djokovic on a longer-term basis.

The pair spent time working together in Spain last month before joining forces in Melbourne this week.

"It made sense to trial it and see if it works. And then we said we'd make a more definitive decision after the tournament," said Murray.