During Andy Murray’s emotional retirement ceremony this summer at Wimbledon, his interviewer, Sue Barker, wondered whether Murray would be keen to return purely as a spectator. She noted he had many options; a spot among the club members, an invitation into the royal box or even the commentary booth.

Murray, however, had other thoughts: “I’d probably be more comfortable sitting up there in a coaching box than somewhere else,” he said, pointing to the seats his own coaching team occupied.

There was never any doubt Murray would go on to be a coach once his career ended, but on Saturday Murray still shocked tennis and beyond with the announcement he will be Novak Djokovic’s new coach and they will work together during the off-season until at least the end of the Australian Open. It is one of the most astonishing coaching partnerships in recent memory.

As two of the leading players of the past 20 years, this pairing is unprecedented. Their own particular history makes it even more fascinating. Murray and Djokovic were born a week apart in the middle of May 1987 and they first met each other as 11-year-olds, with Murray easily winning their first match.

That marked the start of a rivalry that has linked them for a monumental 26 years. They have faced each other 36 times, including seven grand slam finals, with Djokovic winning 25 of their meetings.

While Djokovic smothered Murray to win four of his 10 Australian Open titles and then his fourth consecutive grand slam title at the 2016 French Open, Murray won his first grand slam title at the US Open in 2012 and his historic first Wimbledon title in 2013.

At the height of his career, Murray woke up every day trying to extract every last drop out of his talent in order to catch up with Djokovic, Nadal and Federer.Now, suddenly, they will have to learn how to work together after battling for so long.

“We played each other since we were boys, 25 years of being rivals, of pushing each other beyond our limits,” Djokovic said. “We had some of the most epic battles in our sport. They called us gamechangers, risk-takers, history-makers.

“I thought our story may be over, turns out it has one final chapter. It’s time for one of my toughest opponents to step into my corner. Welcome on board, coach Andy Murray.”

Looking beyond the surprise of this coaching alliance, it is not difficult to see Djokovic’s vision. Along with his talent and monumental work ethic, Murray’s success was driven by his tactical genius and his peerless ability to understand the game, to anticipate his opponents’ decision making and outsmart them.

He left no stone unturned in his career, constantly watching matches and surveying data to improve his game. With his on-court intelligence and passion, his qualities have always seemed a recipe for success as a coach.

This is a fascinating moment for Djokovic as he navigates his final years as a professional. Now 37, he has won everything there is to offer. He showed he can still perform at the highest level this year by willing himself to victory at the Olympic Games, but he also struggled and occasionally looked his age. He finished the year ranked seventh having failed to win multiple titles for the first time since 2005.

The big question surrounding Djokovic is whether he is truly willing to put in the work and endure the sacrifices required to be successful at this point in his career. There are two exceptional young players, Jannik Sinner and Carlos Alcaraz, who will only continue to improve.

With the exception of his other great rivals, Rafael Nadal and Roger Federer, there is no one else who understands those sacrifices and what it takes to be successful in this era as Murray does. Murray is completely unproven as a coach, but he is surely the only person who has the authority to keep a 24-time grand slam champion honest.

Murray’s possible motivations are perhaps even more interesting. It seemed he would take some time to enjoy himself after retirement, but he is a curious person, particularly when it comes to tennis, his lifelong obsession.

After spending so much of his life trying to outdo Djokovic, here comes a rare opportunity to understand his greatest rival, to put their experiences and thought processes together, and to see where they land. The world will be watching.