One glimpsed an image of the near future in men's tennis yesterday when Andy Murray defeated Juan Martin Del Potro 6-7, 7-6, 6-1 in the final of the Rogers Cup in Montreal, one of two major US Open warm-up events. This was likely the first of many times this duo will face each other in championship matches. And it will likely come sooner than later as tennis starts it's slow, yet inexorable, shift from the two-headed dictatorship of Roger Federer and Rafael Nadal to a more democratic rule at the top. In fact, tennis may be on the verge of having its deepest rankings in twenty years

Now this may seem like an odd declaration, what with The Roger having regained the number one ranking and the sport still searching for a player without the surname of Federer or Nadal to lay claim to a Grand Slam title (only twice since the French Open of 2004 has someone else won a GS event - Marat Safin at the Australian Open in 2005 and Novak Djokovic at the Australian in 2008, a period covering 21 tournaments).

But sure enough this change at the top is fast approaching. The Scotsman Murray is now the technical number two player in the world as he leapfrogged Nadal in the standings on the basis of his win in Montreal (there's obviously an asterisk that coincides with this as Nadal has just returned following a two month layoff which caused him to miss Wimbledon).

And Murray, 22, has done much to deserve his ranking. He is the owner of a stellar 50-7 record on the year and is the best hard-court player in the world, having won 31 of 33 matches on the surface this year. And he did reach the finals of last year's US Open where he surprisingly fell flat against Federer, against whom he's had little difficulty, as his six-wins-in-eight-matches attests. I'd be surprised if Murray were not to defeat Federer when they next play in a Grand Slam event.

The 20 year old - though he looks closer to 30 - Del Potro, from Argentina, is also clearly ready to be a threat to win major championships. Consider - he had Federer on the ropes at the French Open two months ago when he led by two sets to one in the semifinals before succumbing to physical and mental nerves. Right now Del Potro's glaring weakness is his lack of conditioning and his susceptibility to wilt in hot conditions. He was outplaying Murray for most of the first two sets yesterday before he was rendered limp in the final set. But if he is able to gain some leg strength to bolster his ferocious and accurate ground strokes, Del Potro will be a threat for the number one position before long.

So where will this leave Federer and Nadal in the next two years? This is where it will be fascinating to watch. Nadal will truly be the "era-overlapping" figure, if he can remain healthy. Though he has already been beset by nagging injuries which will likely be a constant for the remainder of his brilliant career, the guy is still only 23 and the owner of six Grand Slam titles. And if he manages his body, by way of cutting back his grueling schedule, he will be a significant factor for the next three to four years.

And depending on how he fares against the rushing up-and-comers Murray, Del Potro et al., Nadal's "legacy potential" is limitless. If Rafa continues to dominate Federer in their remaining meetings - Nadal is ahead at this point 13-7 - and then maintains against Murray (against whom he's won seven of nine), Del Potro (Nadal has four of their six encounters) and the rest of the next wave in the sport, then the Spaniard's place in the history of tennis will be more than secure. Indeed, what an incredible accomplishment it would be - to be the man who wrestled control of the sport away from Federer and then maintained his standing against a deeper field than Federer faced during his incredible five year reign.

And then there's Federer. There's really nothing he needs to accomplish to burnish his legendary resume. No discussion of the tiresome "greatest ever" list will be without him. So the question is how much longer can he be a threat to win Grand Slam events? Probably another year or two is the most logical response. And if there was something else for him to add to his sterling record, what would it be?

Well, there is one noticeable - well I wouldn't call it weakness - so let's call it a spot on Federer's record - that is, his weak record against top opponents. Not only has Nadal dominated the world's best but Federer's record against Murray is also terrible. Consider - Federer has not defeated a top four seed at a Grand Slam event since the US Open in 2007. So if one played the role of contrarian, the only thing left for Federer to do would be to have another year of at least one Slam win but this time beating Nadal, Murray or the others while this transition is taking place. If he were to achieve that, even the most irrational Federer detractors would have to say he's done everything he had to do.

Whatever happens in Flushing in a few weeks time, men's tennis is lucky to have several players ready to battle for supremacy, to finally challenge Federer and Nadal. It'd be surprising if the US Open doesn't finally provide fans with a thrilling fortnight.

NOTES: The relative strength in the men's game is quite a contrast to the paucity of excitement and lack of consistency that exists with the women. Never so more exhibited than this past week when all the top eight seeds reached the quarterfinals of the men's event in Montreal while only four women did the same at their event in Cincinnati - and on top of that both of the Williams sisters lost early. With a dubious - through no fault of her own - number one player in Dinara Safina - who herself lost in the finals - and the lack of enthusiasm for any event outside the Grand Slams with the Williams sisters, the women's tour, outside of Grand Slam tournaments, is losing relevance.

Switching sports topics, the thrilling PGA Championship that was either won by a brave Y.E. Yang - the pride of Korea - or lost by a choking Tiger Woods depending on one's observations, is also notable for yet another parallel between Tiger and Jack Nicklaus. As I wrote last week about how their comparable careers have been eerily similar, Woods' loss yesterday bring congruity; starting with their first year they won a major, Nicklaus and Woods both had four major-less years through their first 13 seasons.