Predicting who will win tennis' grand slams over the last decade and a half has been as straightforward as it ever has in the history of the sport. For the majority of that time, either Federer, Nadal, Djokovic and, to a somewhat lesser extent, Murray, have shared the honours between them. Collectively, they have won 51 grand slams out of a possible 61 since 2003.

Never before has domination been seen like this on a tennis court by just a few men and without a doubt, the world has witnessed tennis' golden generation and greatest age. It's gone on for so long that it seems inconceivable that it would ever come to an end but like all great sporting triumphs, it sadly can't go on forever.

Novak Djokovic's exit from the French Open at the quarterfinal stage is another reminder that the Big Four can't go on indefinitely, with the first segment breaking apart in front of our very eyes at Roland Garros. Whatever way you look at Djokovic's form over the last two years, it can't be interpreted as anything but a steady decline after going almost two years without making a semifinal at a grand slam.

Even if you were to argue that injury has ruled him out of a sizeable chunk of those two years, it wouldn't take away from the fact that his physical attributes and capabilities are a shadow of what they were. After losing to Marco Cecchinato, Djokovic made a beeline to the post-match press conference where he told reporters he wasn't sure he was going to play on grass this season. It could have been the heat of the moment that contributed towards him saying that and it would be interesting to get his thoughts now after he's had time for reflection.

As it stands, Djokovic is 11/2 to win Wimbledon in the latest tennis odds and it would be a serious blow to the tournament should the 12-time grand slam winner not attend. Djokovic may be the first to currently be exiting the Big Four but it doesn't mean he won't win at least one more grand slam at some stage. Djokovic has an incredible record at Wimbledon having won it three times already so if there was ever a time to make hay whilst the sun is still shining it is now, ultimately, Djokovic has to go to Wimbledon if he wants to try and recapture that winning feeling again.

The Serb's decline has been steady but there may yet be a couple more big days in his career but he certainly can't be labelled as part of a Big Four going forwards. Andy Murray may well be next to fall off the pace after a lengthy layoff following a hip operation with big question marks lingering over his ability to keep on being considered one of the worlds best.

When put into perspective it was always inevitable that these days would arrive when the giants of tennis began to shrink back into mere mortals once more. It's a historic time to witness the end of a reign and also the emergence of the new talent coming through.