In the year since the five top‑ranked men’s players – Andy Murray, Novak Djokovic, Milos Raonic, Stan Wawrinka and Kei Nishikori – arrived in Melbourne with reasonable expectations of challenging for the first grand slam title of the season, the tennis world has been tumble-dried like a 20-foot wave.

Djokovic – once so dominant at the Australian Open – fell in the second round, Murray and Nishikori reached the last 16, Raonic got to the quarter‑finals and only Wawrinka reached the semi-finals. More significantly in a wider context, though, not one of them made it as far as the fourth major of 2017, the US Open. If ever there was a statistic to describe the parlous state of modern tennis, it might be that one. And it could be superseded on 15 January, as there is no guarantee any of them will reach the starting line this year or survive without injury over the course of the tournament.

Roger Federer, who is well placed to defend his Australian title and win his 20th major, identified the brutal truth this week when he said of those players struggling to make Melbourne: “Something tells me that probably two guys out of the top five, six that have been injured for a while now probably won’t make it, because it seems too many guys are fighting something.”Murray, who pulled out of the Brisbane International on Tuesday (after the pre-tournament withdrawal of Rafael Nadal – who is still recovering from the knee injury that forced him out of the ATP World Tour Finals in November – and Nishikori), heads the casualty list.

Djokovic who, like Murray, has not played since the ninth day of Wimbledon last year, is probably the next most vulnerable, carrying an elbow injury that refuses to heal; Nishikori, perennially suspect, nurses a sore wrist and will not feature in Melbourne; Wawrinka has had two operations on his knee – and no warm-up tournaments; and Raonic somehow got on court in Brisbane on Wednesday but was beaten in straight sets by the Australian teenager Alex De Minaur.

Quick Guide Andy Murray's annus horribilis Show February 2017: Murray endures shock fourth-round defeat against Mischa Zverev at Australian Open and on return home is diagnosed with shingles. Returns in Dubai after a month off and wins only title of season. March: Pulls out of Miami Open because of elbow problem and is unable to carry out several commitments after contracting flu. Out for six weeks, also missing Britain’s Davis Cup quarter-final against France. May: With his form on clay shaky, Murray is laid low by a heavy cold and cough before French Open. Recovers to reach semi-finals before losing against Stan Wawrinka. July: Murray is unable to practise four days before start of Wimbledon title defence after long-standing hip problem flares up. Declares himself fit and limps through five matches, but endures his joint earliest exit from SW19 in a decade, beaten by Sam Querrey in quarter-finals. August: Hip injury forces Murray to withdraw from Rogers Cup and Western & Southern Open. Rafael Nadal ousts him as world No1. Murray pulls out of US Open two days before the start, saying he is not fit enough to do himself justice. September Announces he is unlikely to play again in 2017 in order to undergo 'extended period of rest and rehabilitation'. Rules himself out of the ATP World Tour Finals in London.

January 2018 Pulls out of planned comeback at Brisbane International because of pain in right hip. Photograph: Darren England/AAP

It was hardly surprising that in the hours after Murray’s Instagram post laid bare his desperation, Nadal and Djokovic posted heartfelt words of support. “Andy, thank you for genuinely sharing your thoughts and emotions with everyone,’ wrote Djokovic. “I can imagine how bad it feels.” A glance at their collective tumble through the rankings in only 12 months from the top of the mountain paints a picture of suffering and rolling disappointment. Murray has crashed from No1 to 16; Djokovic, No2 last January, has fallen 10 places; third‑placed Raonic is 24th now; Wawrinka has slipped from fourth to ninth; and Nishikori from fifth to 22nd.

Who can be sure where this year’s top five – Nadal, Federer, Grigor Dimitrov, Alexander Zverev and Dominic Thiem – will be in a year’s time?

Raonic observed in Brisbane this week: “If you look at it from just a purely numbers standpoint, you see the guys that play a lot the year before, a lot of matches, 65-plus, maybe even over 70 matches, those guys struggle the following year.”

It seems the game has finally entered the era of uncertainty that is the lifeblood of any sport – although the route to it is littered with bruised spirits. There are 42 over-30s in the top 100, more than in any year since the rankings began in 1973 – but many of the leading contenders are starting to look their age. The 2018 Australian Open will almost certainly throw up shocks to match those of a year ago.

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