Djokovic, on the other hand, requires fresh impetus ahead of potentially his final season, a kindling of the fire as he attempts to surmount the age gap to Jannik Sinner, 23, and Carlos Alcaraz, 21, the two fearless wunderkinds who have usurped him at the summit.

The Serb was alarmingly flat in losing to Sinner in this year’s Australian Open semi-finals, as if stunned by the Italian’s power.

It is difficult to envisage any such listlessness under Murray’s tutelage. On the contrary, the coach’s likely message is that if Djokovic can turn the tables on the next generation once – as against Alcaraz in the Olympic final – then he can do so again.

The doubt is whether Murray can stay calm enough as a sounding board for Djokovic to deliver. His own coaching team required the patience of Job to deal with his mid-match outbursts, as he lacerated them for everything from poor shot selection to not applauding him loudly enough.

Djokovic is no saint in this department either: just ask Goran Ivanisevic, whom he berated furiously in Melbourne in January for failing to look at him. Is Murray the type to sit in his box and accept similar treatment with good grace? Not unless he has undergone some Damascene conversion since retiring.

Celebrity coaches are hardly novel in these settings. Murray savoured his finest results under Ivan Lendl, the inscrutable eight-time major champion who appeared, even amid the convulsions of the 2013 Wimbledon final, as if he would rather be playing golf back home in Florida. It was Lendl’s poker face that offset his pupil’s histrionics and made the relationship succeed.

Murray is, to put it politely, more of an open book. Yes, his tireless encouragement made him a wonderful Davis Cup team-mate. But in the egocentric world of grand slam singles, raw emotion on the sidelines can be a hindrance. Murray needs to suppress his wilder instincts, to recognise that stoicism can be a virtue.

Djokovic is paying Murray the most sincere compliment in calling for his counsel. He has little time to waste, and he has reached the stage where he feels his only option in preventing another Sinner-Alcaraz clean sweep at the majors is to lean on his former adversary.

Unlike career coaches, Murray understands how to shape matches through sheer force of will. He showed it in Australia only last year, when he was yelping in agony at the back of the court. Making light of his metal hip to frustrate Thanasi Kokkinakis with a series of staggering retrievals, he flipped the match on its head and secured victory at a little past 4am in an almost empty arena.

That unquenchable thirst is what he needs to revive in Djokovic. Ever since that Olympic gold in August, Djokovic has lacked his usual intensity, as if realising at some level that he has completed his sport.

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Murray is the figure who can remind him that there is still more history to write, still more distance to put between him and everybody else.

How poetic it would be if it all came together with a record-extending 11th Australian Open triumph.

Murray has reason to believe he is cursed in Melbourne: no other player, male or female, has competed in five finals at the same major without winning. He, too, has an itch to scratch, and who better to do it with than his once-implacable rival?

The Telegraph, London

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