With a formidable 21 Grand Slam titles between them, Roger Federer and Rafael Nadal are the dominant forces on the ATP tour. In reality, the ‘Top Ten’ of male tennis has its own sub-division. Nadal and Federer aside, the remaining eight players total just two Grand Slams between them. So, who will break the Swiss Spanish stranglehold on male tennis?

Tennis buffs ran out of superlatives to describe Novak Djokovic’s devastating Australian Open 2008 form, which saw him clinch a maiden Grand Slam title. His form since then has petered out more than a Tim Henman second serve.

A dip following initial success seems to be customary for youngsters across many sports – Wayne Rooney’s bursting onto the global scene at Euro 2004 was followed by a mediocre season by his standards, and all the hype following Amir Khan’s Olympic and first few professional fights success was given a dose of stone cold reality, when he was floored by Breidis Prescott in 45 seconds.

2009 has been a disappointing season for Djokovic; plagued with fitness problems and exhaustion, he bowed out of the Australian Open in acrimonious fashion to Andy Roddick. Djokovic vaguely cited muscle cramps and soreness as the reasons for his retirement, but the problems were not a one off - his dependency on the trainer following his tie with Tommy Robredo at the 2008 US Open drew lots of criticism.  

Novak’s game has become altogether more passive, his ground strokes lack conviction, and he is starved of any confidence in his own abilities – evident in the second set tiebreak against Tommy Haas at this year’s Wimbledon. If he is to avoid being mentioned in the same vein as Marat Safin and Juan Carlos Ferrero, players who failed to live up to their true potential and fell by the wayside, his consistency will have to improve dramatically, along with his fitness.

Andy Murray’s rise to prominence over the past few seasons has left many pundits tipping him to become Rafael Nadal’s major rival when Roger Federer retires. As early as 2005, when Murray’s career was in its infancy, John McEnroe commented, ‘With Murray the sky's the limit’. His record over his closest rivals is impressive – he captured the Madrid Masters title in 2008, and defeated Nadal and Federer on the way to victory in the 2009 Capitala World Tennis Championship.

But there is a key ingredient missing in the Murray concoction, and that’s a Grand Slam title. Murray succumbed miserably to Roger Federer in the final of last year’s US open, and was ousted by Andy Roddick at the semi-finals of SW19, when he was hot favourite. A winning ‘know how’ or mentality in Grand Slams is a priceless attribute, and what divides the good from the very best. A Grand Slam, as Federer testified, is a different ‘animal’ – the two week slog and media pressure requires exceptional mental strength to thrive.

But if Murray can continue to hone the offensive aspect of his game, and negate a resurgent Andy Roddick, he will be amongst the favourites for the US open. Murray must also keep a cool head. The British media is notorious for hyping up all if its sportsman with an iota of talent, resulting in inordinate pressure. The longer Murray goes without a Wimbledon title, the harder it will become, as Tim Henman knows only too well.

Then there’s the rest. Juan Del Potro’s gangly frame may not make him the most mobile player, but his solid baseline play and powerful ground strokes have seen him endure a meteoric rise up the rankings to 5^th, and reach the semi-finals of Roland Garros where he took Roger Federer to a fifth set. The question is, as with every player heralding from a clay-court specialist country, is whether he can make the successful transition onto all surfaces. The Argentinean followed up his French Open exploits with a lacklustre straight sets defeat to the un-seeded Lleyton Hewitt at SW19. At just 20, however, time is on his side.

Andy Roddick received his fair share of plaudits for his titanic effort in the Wimbledon final, and deservedly so. But the thing that eluded him, and what distances Roddick from greatness, was knowing how to cross the winning line. At 6-2 up in the second set tiebreak, he had a chance to put the match out of Federer’s reach, and failed. Although Roddick recovered admirably to take the match into fifth-set sudden death, by the end the American was flagging. Having reached three Wimbledon finals, and succumbed to the Swiss wizard in each one, there’s a feeling that Roddick lacks the mental edge. With an impeccable serve and such powerful ground strokes, Roddick should have capitalised on his sole Grand Slam triumph back in 2003 at the US Open.

In truth, there’s no-one else capable of disrupting the Federer and Nadal dominance. The rest have huffed and puffed, but failed to find any real consistency. Jo Wilfred Tsonga’s superb athleticism and robust ground strokes make him a potential spanner in the Federer Nadal works, but he’s had an indifferent Roland Garros and Wimbledon. The likes of Robin Soderling and Fernando Gonzalez have all looked desperately out of their depth in their Grand Slam final appearances.

If Federer and Nadal are playing to their full potential on the day, there’s little prospect of anyone overcoming them. If Nadal can rid himself of the knee injuries that have scuppered his 2009 slam hopes, and Federer…well continue being Federer, the outlook is bleak for the rest, at least for the next few years. It would take Djokovic 2008 Australian Open and Murray 2008 US Open form to stand a chance.