<table> </table> Call this the wild card U.S. Open.</p><p>This country&#8217;s greatest tennis tournament, the fourth and final grand slam event of the professional tennis year, can often be unpredictable. But there are a couple of factors in play that could make this Open, which starts Monday and runs through Sept. 7 at Flushing Meadows, N.Y., an even more wide-open affair.</p><p>Foremost &#8212; and this applies to both the men&#8217;s and women&#8217;s draws &#8212; is the effect the Olympic Games will have on the players who competed in Beijing. Sure, it&#8217;s possible that Spain&#8217;s Rafael Nadal and Russia&#8217;s Elena Dementieva got a big boost in confidence from their gold medal performances. But it&#8217;s also possible that they, along with the many other Olympic competitors, will arrive at the U.S. National Tennis Center with varying degrees of fatigue.</p><p>&#8220;It&#8217;s hard to say how much (the Olympics) takes out of the players,&#8221; said John McEnroe, former four-time U.S. Open champion and lead tennis analyst for CBS&#8217;s coverage of the tournament. &#8220;It will definitely be an issue.&#8221;</p><p>The other X-factor, this one affecting only the men&#8217;s draw, is the vulnerability of four-time Open champ Roger Federer. He hasn&#8217;t won a major tournament this year, and to say he&#8217;s been beatable would be an understatement, as demonstrated by his surprising quarterfinal loss to American James Blake in Beijing.</p><p>That makes Nadal the favorite to win a third grand slam event this year, to go with his French Open and Wimbledon crowns &#8212; and that gold medal.</p><p>The women&#8217;s title, as usual, appears to be there for the taking, what with world No. 1 Ana Ivanovic nursing a hand injury, Maria Sharapova out with a bum shoulder, Serena Williams still fighting a sore knee and Venus Williams not having played much.</p><p>&#8220;Nadal is certainly the favorite,&#8221; McEnroe said. &#8220;But last year&#8217;s finalists (Federer and Novak Djokovic) both have reasons for wanting to win. It would be hard for me to picture one of those three guys not winning it.</p><p>&#8220;With the women, when I see the Williams sisters playing the way they&#8217;re capable, they&#8217;re the favorites.</p><p>&#8220;But it&#8217;s pretty unpredictable.&#8221;</p><p><hr class="infobox-hr-separator" /> <div class="infobox"> <strong>1 CAN RAFAEL NADAL FINISH OFF A NEAR-PERFECT SEASON?</strong> History says it will be tough. The gritty Spaniard has never advanced past the quarterfinals at the Open. Typically, he comes into the tournament fatigued from a long summer of play, and the quick, hard courts in Flushing Meadows never seem to suit his game. However, he still had plenty of juice to win gold in Beijing. And no one, perhaps in the history of the game, competes with such ferocity. A victory would seal one of the great years in men&#8217;s tennis history.</p><p><strong>2 CAN ROGER FEDERER SALVAGE A LOST SEASON?</strong> If he does, it will certainly be considered an upset, which is astonishing to say, given the man&#8217;s greatness over the last five years. &#8220;It shows how precarious tennis can be,&#8221; said U.S. Davis Cup captain and TV analyst Patrick McEnroe, John&#8217;s brother. &#8220;If you lose a little confidence in your shots, you start to second-guess yourself. All of a sudden, you see players going out there believing they have a shot.&#8221; Federer is going to have to pick it up a notch to get by contenders like Novak Djokovic and Nadal, and thus far he hasn&#8217;t shown that ability.</p><p><strong>3 WHO WILL STEP UP FOR THE WOMEN?</strong> Difficult to predict. Ana Ivanovic hasn&#8217;t been the same since winning the French Open and ascending to the No. 1 ranking. But having to miss the Olympics because of her injury could help in the long run. Serena Williams had to retire in a recent final in Stanford, Calif. because of her knee. Then she fell to Elena Dementieva in the quarterfinals in Beijing. The Olympics was the first tournament Venus Williams had played in since winning Wimbledon, and she also fell in the quarters. The momentum would probably have to go with Dementieva, who posted the biggest win of her career in taking home Olympic gold.</p><p><strong>4 DARK HORSES? </strong>On the men&#8217;s side, it would have to be Argentinean Juan Martin Del Potro. He&#8217;s won four straight tournaments since Wimbledon, including two hard-court events in the U.S. He&#8217;s quickly moved to No. 24 in the world. American James Blake is coming off a semifinal run at the Olympics, where he upset Federer, but he&#8217;s too streaky to make it through the entire two weeks.</p><p>For the women, Russian Dinara Safina has had a very solid year that has included an appearance in the French Open final, three tournament wins and a silver medal performance in Beijing.</p><p><strong>5 (EXPLORERS SPECIAL) WHAT ARE THE BRYAN BROTHERS&#8217; CHANCES?</strong> Bob and Mike Bryan, who have been members of the Explorers each of the last four World TeamTennis seasons, will certainly be hungry. They haven&#8217;t won a grand slam tournament this year and had to settle for bronze at the Olympics.</p><p></div>