Can Maria Sharapova repeat as U.S. Open champion? (Getty Images)

Should world No. 1 Roger Federer take the U.S. Open men's title on Sept. 9 at the National Tennis Center in Flushing Meadows, N.Y., he will become the first man in the modern era to win it four straight times (Bill Tilden won six in a row in the 1920s). It will also mark 12 Federer wins in the last 17 men's Grand Slam events and leave him just two shy of Pete Sampras's modern record at the age of just 26.

Challengers are hanging their hopes that some mortal results this summer from Federer are a sign he could be headed for a first Open defeat since losing to Argentina's David Nalbandian in 2003. The Swiss star lost to Novak Djokovic in the Rogers Cup final in Montreal, eked out a win over Lleyton Hewitt in Cincinnati and, best of all for the contenders, even had struggles against Marcos Baghdatis and Nicolas Almagro.

The women's side is another matter entirely. There has been a different U.S. Open winner in each of the last six years; with five of those champions entered this time around (Kim Clijsters has retired).

It's likely that one of the five will win again, though young Serbian stars Jelena Jankovic and Ana Ivanovic have the best chances at making it seven unique winners in a row.

The recent parity on the women's side has meant the No. 1 seed heading into the tournament has won just once in the last nine years, a trend Belgian Justine Henin will need to buck.

WOMEN

THE FAVOURITES

Justine Henin, Belgium, No. 1 seed
Best result at U.S. Open: Champion (2003)
2006 result: Finals
It sounds strange to say that the world No. 1 might need help from others to win, but it could be true. Otherwise, she could face the unenviable task of beating both Serena and Venus Williams before even reaching the final, and her only U.S. Open win came in a year when the Williams sisters were absent. She's 5-6 against Serena but has never beaten her on the hardcourt, and is just 1-7 against Venus, with the lone victory on clay. On the plus side, she beat Serena at both the French Open and Wimbledon.

Maria Sharapova, Russia, No. 2 seed
Best & last result at U.S. Open: Champion
Conventional wisdom has Sharapova breezing to at least the quarters in the perceived weaker side of the draw. Will she look past opponents because of her draw? Potential semifinal opponents Nadia Petrova and Svetlana Kuznetsova have beaten her on hardcourts before.

CONTENDERS

Jelena Jankovic, Serbia, No. 3 seed
Best & last result at U.S. Open: Semifinals
Reached the semifinals last year in New York, a precursor to a tremendous year. She gave Henin all she could handle in Toronto's final, and has done well against potential opponents the Williams sisters and Elena Dementieva, if not Henin (0-7 lifetime).

Ana Ivanovic, Serbia, No. 5 seed
Best & last result at U.S. Open: Third round
A tremendous summer - WTA win in Los Angeles, finals at the French and semis at Wimbledon - could end in less stellar fashion. She faces a possible round of 16 match against Venus Williams, and potential opponents after that include two of Dementieva, Jankovic, Henin or Serena Williams. Of those five women, she's only previously beaten Jankovic.

Serena Williams, United States, No. 8 seed
Best result at U.S. Open: Champion (1999, 2002)
2006 result: Fourth round
Her performance in Australia showed that the combination of her talent and self-belief can take her to a Grand Slam win without much in the way of preparation. Still, it will be a tall order to win in Flushing after not playing since Wimbledon. Added to the normal question marks of conditioning and focus will be the status of the left thumb she sprained in London.

Venus Williams, United States, No. 12 seed
Best result at U.S. Open: Champion (2000-01)
2006 result: Did not play
Her Wimbledon win has her back in contention, but tendinitis in her knees limited her summer play. She hasn't won a non-Wimbledon Slam since 2001 and her only two U.S. Open appearances in the last four years produced middling results. Her path to a possible semifinal match against her sister (or Henin) is no gimme, but it's not overwhelming either.

DON'T FORGET

Svetlana Kuznetsova, Russia, No. 4 seed
Best result at U.S. Open: Champion (2004)
2006 result: Fourth round
The inconsistent Russian hasn't made it past the fourth round since her surprise 2004 Open win. Consecutive quarter-final appearances in Paris and London could suggest she's bouncing back. She got some needed activity in Toronto, though she bowed out in a tough three-set loss to young Tatiana Golovin of France in the quarters.

COULD MAKE SOME NOISE

Anna Chakvetadze, Russia, No. 6 seed
Best & last result at U.S. Open: Fourth round
The young Russian has posted best-ever results in each of the three Grand Slams this year. The draw should see her clear through to the quarters, where she may have to get past countrywoman and nemesis Sharapova.

MAYBE NEXT YEAR

Nicole Vaidisova, Czech Republic, No. 9 seed
Best result at U.S. Open: Fourth round (2005)
2006 result: Third round
Barely 18, Vaidisova has reached at least the quarters of every Grand Slam this year, but she's been out since Wimbledon with illness. Still, a first-ever career match against in the round of 16 against Sharapova, who she's been compared to, would be mighty intriguing.

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Roger Federer is seeking his fourth straight U.S. Open title. (Getty Images)

MEN

THE FAVOURITE

Roger Federer, Switzerland, No. 1 seed
Best result at U.S. Open: Champion (2004-2006)
2006 result: Champion
His opponents from the round of 16 to the final could conceivably be Richard Gasquet, Andy Roddick, and Tommy Haas or James Blake. While he's owned Gasquet and Roddick in recent years (19-2 overall), they're still capable of the upset. No reason to think he won't reach the final, but he'll get tested along the way.

CONTENDERS

Rafael Nadal, Spain, No. 2 seed
Best & last result at U.S. Open: Quarter-finals
Has produced riveting tennis with Federer on clay and grass, but needs a breakthrough past the quarters at the U.S. or Australian Opens to be considered in Federer's echelon regardless of time of year. There's a strong chance that could happen in New York considering his draw, but first he may to need to beat compatriot David Ferrer and Chilean Fernando Gonzalez, who has beaten him in two previous matches on the surface.

Novak Djokovic, Serbia, No. 3 seed
Best result at U.S. Open: Third round (2005-06)
2006 result: Third round
His combination of accuracy and decent power led to consecutive wins over Roddick, Nadal and Federer in Montreal for the title. The draw makers haven't done him any favours here. His first match is against friendly Croatian rival Mario Ancic, who always plays him tough. After that, he may have to defeat the likes of Radek Stepanek of the Czech Republic, past Open champ Lleyton Hewitt and Spaniard Tommy Robredo just to reach the semis.

Nikolay Davydenko, Russia, No. 4 seed
Best & last result at U.S. Open: Semifinals
He's on the same half of the draw as Federer and Roddick, but would only face one of them, and not until the semis. Since 2005, he has reliably gone deep into the Grand Slam events, though not yet to a final. The recent questions over a loss to low-ranked Martin Arguello in Poland could motivate him in New York. Lost to James Blake in August, a potential quarter-final opponent.

Andy Roddick, United States, No. 5 seed
Best result at U.S. Open: Champion (2003)
2006 result: Finals
The American made a splash with new coach Jimmy Connors last year, reaching the Open final. The last man before Federer to win the tournament, they could meet in the quarters. Just to reach that point Roddick may have tough matches against big Ivo Karlovic and No. 9 Tomas Berdych. Has had an up-and-down summer - winning in Washington but suffering upset losses to Ferrer and Canadian Frank Dancevic. Will go as far as his serve takes him.

Fernando Gonzalez, Chile, No. 7 seed
Best result at U.S. Open: Quarter-finals (2002)
2006 result: Third round
The American Blake is seeded one spot of ahead of Gonzalez and will get boisterous support, but the Chilean with the wicked forehand has a better shot of advancing. Showed his hardcourt prowess by taking down Hewitt, Blake, Nadal and Haas en route to the Aussie final in Melbourne. Favoured to get past the likes of mercurial Marat Safin and Ivan Ljubicic and into a quarter-final showdown with Nadal.

DON'T FORGET

Lleyton Hewitt, Australia, No. 16 seed
Best result at U.S. Open: Champion (2001)
2006 result: Quarter-final
Always competitive, Hewitt is healthy and has been playing well under former Federer coach Tony Roche. Federer considered himself "a little bit lucky" to beat the Aussie in Cincinnati in mid-August. Hewitt's never been worse than a quarter-finalist at Flushing since 2000. Could face Djokovic in the quarters, a rematch of their titanic Wimbledon struggle.

COULD MAKE SOME NOISE

Guillermo Canas, Argentina, No. 14 seed
Best & last result at U.S. Open: Fourth round (2004)
Canas hasn't played at Flushing since 2004 due to a suspension for using a banned diuretic. He beat Federer twice in March. Was a non-factor in Montreal and Cincy, but based on his seeding, is expected to reach the round of 16 against Davydenko. At 29, the plucky Argentine knows his Slam opportunities are limited.

MAYBE NEXT YEAR

Andy Murray, Scotland, No. 19 seed
Best & last result at U.S. Open: Fourth round
The exciting young Scot was bounced early in Montreal and Cincy, unable yet to get back on track from a sprained right wrist he injured in May. Grizzled vet Jonas Bjorkman of Sweden, and either Canas or Slovakia's Dominik Hrbaty stand in his way of just matching last year's result.