AND then there was one. The Big Four of Novak Djokovic, Roger Federer, Rafa Nadal and Andy Murray has been whittled down of late.

Much like the unfortunate Black Knight in the Monty Python sketch who seeks to shrug off the loss of limbs (tis but a scratch!), the Big Four have tried to be resilient but succumbed to injuries inflicted by brutal duels with resolute opponents and unforgiving surfaces.

One has survived, relatively unscathed. The three others have had surgeons on their frequent callers’ list.

Djokovic will open proceedings on the Centre Court against 19-year-old Jack Draper of England in Wimbledon 2021. The youngster’s chances are limited. The bookmakers list Djokovic odds-on to win the tournament, that is, he is considered more likely to take the title than all the other competitors combined.

This owes much to the Serb’s brilliance as his claims to being the best tennis player of all time are increasingly persuasive. But it is also a testimony to his fitness. Djokovic, gluten-free and as lean as a hyperactive stick insect, can outplay opponents but he can also outlast them.

Both traits were shared by his companions at the elite end of the game. No more. Federer, in his 40th year, cut short his French Open and was knocked out early in Halle after coming back from knee surgeries last year. Nadal has simply not travelled to London, preferring to rest up for the hard court season that takes a particular toll on his knees.

Murray advances on Wimbledon with some trepidation after a series of operations that have sought to solve a hip issue. His body has had to accommodate strains, putting stress on other parts of his anatomy.

It is impossible to predict with any accuracy how far the 34-year-old Scot will progress in a tournament that he has won twice and at a venue where he also garnered an Olympic gold and silver medal in 2012.

It is sobering to note that Murray has not played in the men’s singles since 2017. He hobbled out then in a five-sets defeat to Sam Querrey, an American with the serving power of an entrenched siege gun and similar mobility.

The imponderable for Murray is not how to return the serves of those big hitters who are particularly dangerous on grass or how to combat the more subtle players such as his first round opponent Nikoloz Basilashvili of Georgia.

The unknowable is how he will recover after matches. Grand slams demand seven victories - over a possible five sets - in 14 days. It is a schedule that depletes the most fit.

Murray’s ambition, therefore, will be to amass as many matches at Wimbledon and elsewhere in the summer. He has to build the recovery process into his body. However, his skills remain extraordinary and his movement was excellent in his two matches at Queen’s.

Much has been made of the possibility of Murray meeting Djokovic in the semi-finals. This would be extraordinarily heartening as it would mean that Murray had won five matches and was recovering well and, secondly, because he does not fear his contemporary on grass.

The Scot has taken a few bloody noses from the Serb over the years, particularly in Australian Open finals, but he beat Djokovic at Wimbledon to win his first title there in 2013 and he defeated him en route to Olympic gold in 2012. His expectations, however, wil be more modest this week even though his desire to compete is unaffected by aches or pains.

Murray’s innate gifts and unwavering will offer him the possibility of a run deep into the tournament but the questions over his body remain unanswered.

His history at Wimbledon, though, is sprinkled with magic moments and there will be at least one more when he is welcomed back by an adoring crowd after his absence.

The ghosts of victories past, the traces of tears shed and the tingling excitement of Oor Andy at the home of tennis have found a place in the national psyche.

However, it is too much to even hope for ultimate triumph though veteran Murray watchers - aren’t we all? - will be prepared to be surprised.

So who will prevail in the gentlemen’s singles?

It is unusual and normally pointless to look outside the Big Four. The last person to win the title outside the quartet was Lleyton Hewitt in 2002.

A generation of players were once touted by commentators and coaches then dismissed by the the Big Four. There were talents such as Juan Martin del Potro, a genuine potential great, whose US Open victory in 2009 is a cause for poignant reflection rather than a foundation for future triumphs. The Argentine has been cursed by injury and will not play at Wimbledon this year.

The same fate is shared by Milos Raonic, Murray’s victim in the 2016 final, who finds that repetitive injury thwarts every move forward. Grigor Dimitrov has shown his class but not his resolve. Nick Kyrgios remains hugely entertaining but ultimately a sideshow rather than the main event.

There are signs, though, that the new generation may capitalise on their talents and the diminishing threat of a largely hobbled Big Four. It will not be this year for Dominic Thiem, who won the US Open, admittedly after Djokovic was thrown out the tournament. The 27-year-old Austrian is injured and has scratched.

Others have possibilities. Stefanos Tsitsipas showed guts and guile in the French Open final, losing to Djokovic after taking a two set lead. This loss will have piqued the 22-year-old’s ambition to win a grand slam.

The Greek was was less than pleased at Djokovic’s time out after the second set in Paris and his apparently miraculous recovery from an unspecified ailment. There is a genuine grievance in the youngster’s breast which always adds something to athletic competition.

Daniil Medveedev, too, will have his hopes. His early departure from Halle serves as as a warning to potential supporters but the 25-year-old Russian is seeded No.2 for a reason. Indeed - in a further reference to the Big Four - he is the first world No.2 not to be called Federer, Murray, Djokovic or Nadal since July 2005.

He reached the Australian Open final this year - almost inevitably beaten by Djokovic - but was triumphant against the Serb, Nadal and Federer at the world tour finals last year. He should have the maturity to withstand the pressures of the most prestigious event of them all but he has not yet been beyond the third round in SW19.

There are two other viable contenders among the younger crew. Sascha Zvereev, 24, and Matteo Berrettini will have advocates. The German has improved his conditioning but has the bad habit of losing close matches and not being at his best when facing the best. This is not a recipe fro grand slam success.

Berrettini carries a significant weapon in his serve. He used it to to great effect when winning Queen’s, playing the sort of grass court game that preceded the BIg Four. The 25-year-old may cause an upset or two but winning the title seems unlikely.

This brings the conversation back to half of the four.

Federer, seeking his ninth Wimbledon title, seems to be on a last crusade. His eagerness to seek Olympic gold means that we will have the Swiss player beyond Wimbledon and into Tokyo but this is surely the last lap for a legend.

Federer played beautifully in the final two years ago against Djokovic and came up short. There is no reason beyond sentiment to suggest he can go one better in 2021.

This leaves Djokovic as a commanding favourite. He has won five Wimbledon titles, 19 grand slams (one short of Nadal and Federer), a Davis Cup and has a winning all-time record against his rivals.

There are no weaknesses in his game. His serve has improved immeasurably, he and Murray are the best returners of the modern era, he is strong off both sides and he defends with an implacable toughness.

He also endures. Once Djokovic was known for quitting during tournaments - mostly with eye or breathing issues - much to the derision of his opponents. But now he is regarded as indefatigable, possibly invincible.

The making of history lies before him. There were once four. Djokovic is now the one.