The greatest light-heavyweight of them all, Archie Moore, was 47 and still champion of the world when he explained better than anyone – before or since – why so many sporting immortals refuse to go gently into the good night.

At this point the siren call of family and the easy life was deafening. Moore also knew his wife yearned for him to retire, and he adored spending time with his young daughters “lest they forget that love and life go hand in hand”. Yet the mere thought of fighters half his age wanting his belts stirred the warrior in him once more.

“I’m still the old mongoose in there trying to outwit and outhit the younger guys,” he said. “I’m like the drunk in the bar who wants one more for the road. I want one more knockout to add to my record and then just one more after that. Some people say it’s great when a man retires undefeated. But a champion should fight to the finish and go out with his hands cocked just as he came in. It’s the proper exit and I think it may be mine.”

And so on Moore went, for another three years, taking on all-comers including a young Muhammad Ali, before finally retiring at 50 after his 186th career victory.

I thought of Moore’s words while watching Novak Djokovic suffer a shock defeat to world No 123 Luca Nardi at Indian Wells last week. And again as the two young contenders for his No 1 crown, Jannik Sinner and Carlos Alcaraz, duked it out on Saturday night – with Alcaraz winning that duel in three sets before swatting aside Daniil Medvedev 7-6, 6-1 in Sunday’s final.

With it came a recurring – and increasingly open – question: for how much longer can Djokovic summon the warrior energy to keep winning multiple grand slam titles every year?

It wasn’t simply that Djokovic endured the worst defeat of his career in a major event against Nardi. It was the manner of his third defeat in 11 matches in 2024. No one is better in clutch moments than the Serb. But against Nardi he reverted to catenaccio tennis, hitting only two winners and two unforced errors in the decisive final set. His opponent, by contrast, smashed 16 winners to four unforced errors.

There was something else, too. Usually the longer the point, the more tennis’s iron man asserts himself. But against Nardi, Djokovic won only 13 of the 37 rallies that went nine shots or more. Afterwards he admitted graciously that his opponent deserved to win. But, tellingly, he added: “My level was really, really bad. I made some really terrible unforced errors.”

There were familiar echoes of Djokovic’s comments after his Australian Open defeat against Sinner, where he hit 54 unforced errors in a four-set defeat. “I was, in a way, shocked with my level, in a bad way,” he said.

For now, at least, it is premature to talk of the torch being passed to the next generation. But, perhaps for the first time, there is a sense that the tennis gods are scratching around for kerosene and a lighter.

It was an issue that Djokovic acknowledged before Indian Wells when he spoke of his sadness at the impending end of tennis’s golden era of him, Roger Federer, Rafael Nadal and Andy Murray.

“We all know that those moments will come for all of us,” he said. “But when they actually come, and when you actually understand that that’s it – that Roger finished his career, Rafa and I are probably not going to play much more, it’s kind of one era comes to an end and it’s sad.”

There will be those who point out that Djokovic won three grand slam titles as recently as last year, as well as the end-of-season ATP Finals. That he has had early season wobbles before – including a defeat against the Japanese player Taro Daniel at Indian Wells in 2018 – and then come back to win grand slam titles. And that these days he concentrates most of his focus on the slam tournaments.

And while all that is true, not even Djokovic – who turns 37 in May – will be able to defy father time forever. The bookies’ odds are starting to reflect that. Alcaraz is favourite across the board for the French Open, while some also make the Spaniard the shortest price to retain the Wimbledon title he won in a five-set epic against Djokovic last year. Both he and Sinner respect the Serb, sure. But they don’t fear him.

Djokovic, meanwhile, confirmed on Saturday that he was skipping the Miami Open this week, an event he has won six times, saying: “At this stage of my career, I’m balancing my private and professional schedule.” A subsequent tweet from the tournament director, James Blake, suggested the Serb had opted to put his family first.

That is entirely understandable. Indeed, it is admirable. It also gives him more time to regroup and stoke up the competitive fires again. Serial Djokovic watchers will remember that after he completed a career grand slam by winning the French Open in 2016, he admitted he lost motivation. He did not win a major title for the next two years. No doubt the sting of the Nardi defeat will stir him up again.

Whatever happens next, we can say this for certain: watching tennis’s old mongoose trying to outwit and outhit the younger generation, looking for one more grand slam title for the road, will make this year’s French Open and Wimbledon even more compelling than usual.