Hardcourt defence begins for Federer

As the hardcourt season begins, Roger Federer should be wary of the threat posed by Rafael Nadal and Novak Djokovic.

Roger Federer practices after arriving at the Rogers Cup in Toronto.

Those envisaging an imminent changing of the guard at the top of men's tennis will be watching the movements of Roger Federer, Rafael Nadal and Novak Djokovic during the North American hardcourt season which, after a low-key opening in Indianapolis last week, began in earnest in Toronto yesterday with the Rogers Cup.

Federer, who surrendered his Australian Open title to Djokovic at the start of the year and lost his cherished Wimbledon crown to Nadal in an epic final in London earlier this month, is now focusing on retaining the US Open championship which he has won for the last four years. If the Swiss master is deposed at Flushing Meadows next month by either the rampant Nadal, who is currently on a winning streak of 24 matches, or the powerful Djokovic, then a magnificent reign as world No1 - which is approaching five years - may be coming to an end.

Djokovic asked the first serious questions about Federer's dominance in Toronto a year ago when the precocious Serb beat him in the final after defeating Nadal in the semis. Federer's emphatic response was to win the following week's Masters Series event in Cincinnati on his way to his familiar fortnight of glory in New York. Nadal's stunning Wimbledon win, coming only four weeks after the Spaniard had slaughtered Federer in the final of the French Open, is the biggest signal yet that Federer has had his best days.

Now it is the job of the two heirs apparent to the crown to force that message home. Firstly in Toronto or Cincinnati and then, more importantly, in New York. This year's programme is complicated by the Beijing Olympics which follow on from Cincinnati and have attracted 17 of the world's top 20. It is a big ask for potential US Open winners to go in search of a gold medal on the other side of the world immediately before the start of the last grand slam of the season.

Andre Agassi won the Olympics in 1996 when they were held just down the road in Atlanta, but the double US Open champion lost to Michael Chang in the semi-finals at Flushing Meadows that year. When Yevgeny Kafelnikov struck gold in Sydney in 2000 - the year after he captured the Australian Open title - the Games were held after the US Open. Federer finished fourth that year but did not feature in Athens four years later.

His performance in Beijing as he seeks to fill in one of only two blank spaces on his CV - the French Open is the other - may be the biggest indicator of all about his US Open prospects. Of the world's top eight all but Argentina's David Nalbandian have travelled to Canada for this week's $2.6million (Dh10.2m) showpiece, meaning Britain's Andy Murray, ranked ninth, is promoted into one of the slots awarded a first round bye.

The key to the draw was where Djokovic would be placed. The world No3 came out in Nadal's half to potentially create a repeat scenario of what happened 12 months ago. He must overcome Murray if both youngsters reach the quarter-finals, while Nadal is scheduled to face his fellow Spaniard David Ferrer in the last eight. Prominent in Federer's top half of the 56-man field are Andy Roddick, who won the Dubai Championships in March, another American James Blake and Russia's Nikolay Davydenko, whose lofty ranking of fourth in the world rarely creates more than a ripple of interest, unless controversial gambling irregularities are being discussed.

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