AT the moment Rafa Nadal dropped to the floor of the Arthur Ashe court in glorious realiation of one his greatest grand slam triumphs, Andy Murray's world shifted again.

It would be unfair to overly emphasise how the Scot's wondrous year came at exactly the same time as Nadal's enforced lay-off with a knee injury which threatened his career. After all, Murray could only defeat what was put in front of him - and that happened to be two of the greatest players of all-time. Roger Federer in the Olympic final and Novak Djokovic in last year's US Open and at Wimbledon, were quite brilliantly put to the sword.

Yet Nadal's sensational return to fitness and form has sent a cat scurrying into the pigeons like never before, as focus already begins to sharpen towards the major battles of 2014. This magnificent Mallorcan was supposed to be finished. His knees were shot.

With Federer's star fading before his failing eyes, the Andy and Novak show was supposed to be the only one in town. Steve Darcis made us all think Nadal was on a hiding to nothing at Wimbledon, dumping the now 13-time slam winner out in the first round. Then, something remarkable happened.

Changing his game to combat his left-knee problems, Nadal came out fighting - and left a trail of destruction in his wake.

This new-look Spaniard, who plays with more aggression and desire to make points short and brutal, laid the platform for his remarkable return. The way Djokovic was dismantled with such aplomb drew gasps from planet tennis. Not many run the Serb ragged like this. His ball striking, most notably on the forehand side, was quite breathtaking.

His dramatic yet utterly deserved four-sets win, a triumph which at the end saw Djokovic, one of the fiercest competitors of all time, almost waving the white flag after a chilling, error-strewn display, sent a serious warning to Murray and any others who want to stand in his way.

In 2011, before the world No.2's injury woes really hit hard, he met the Scot in the semi-finals of the French Open, Wimbledon and at Flushing Meadows. Murray was left heartbroken in all three.

It does go without saying that the British No.1 is a far different prospect now. He's a better, more experienced campaigner with a coach in his corner - in the iron shape of Ivan Lendl - who has brilliantly guided his path to glory.

Back at Wimbledon two years ago, he had chances but blew them. The Murray of 2013 is a different animal and, as a born competitor and fighter, challenging Nadal will be something to relish.

What Murray recognises - the pair are good friends and the world No.3 tweeted his praise for Nadal yesterday - is that the Spaniard will go down as one of the all-time greats of the game. Now just four grand slam titles behind Roger Federer and with a few years to play with, only a fool would bet against the Swiss being toppled in the next few years.

Of course, considering the state of his knees, it's dangerous to get too far ahead of oneself. There were, and still remain, serious doubts about how long the 27-year-old can keep pounding his body.

The glorious glimpses on show here, though, have everyone hoping there will be more to come. It looks like he will eclipse Djokovic as world No.1 by the end of the year and Federer's grand slam tournament tally is in his sights.

"For a few reasons this season is probably the most emotional one in my career," said Nadal. "I never thought that something like this could happen. I just was excited to be back on tour. I felt that I did everything right to have my chance here. It means a lot for me have this trophy with me.

"It is just amazing. I want to thank to everybody who helped me to make that possible. For me, the number of titles I have is much more than what I ever thought, what I ever dreamed I could have. I said that before, when I had few slams less, but it is true.

"Can I catch the others? Let me enjoy this one first. The only thing I can say is the same thing I do every time. I am going to keep working hard so I can have more chances in the future to be competitive and win tournaments like this one. You never know when it starts, when it finishes, but 13 is an amazing number."

Toni Nadal, the world No.2's uncle and coach added: "I never hoped for such a successful run. We had many problems and I couldn't think that seven months later Rafa could be where he is now."

For Djokovic, such a brilliant warrior who had his moments - most notably winning a spellbinding 54-shot rally in the second set - his time will come again. The 26-year-old's display here mirrored his year on the tour, sprinkled with success but too inconsistent to repeat his all conquering form of 2011.

"Thirteen grand slams for a guy who is 27 years old is incredible, " conceded the Serb. "He's definitely one of the best tennis players ever to play the game, looking at his achievement and his age at this moment. He still has a lot of years to play. That's all I can say. I made mistakes but he played better than me. I will come back stronger."

So Rafael Nadal is back. And fantastic plotlines are already being drawn. "I think if he stays healthy he can easily win four or five more, no doubt about it," said John McEnroe. "Let's hope that he stays healthy because it would be great for our sport - and somebody's going to have to step up."

Andy Murray, it's over to you.