NEW YORK -- The conventional wisdom surrounding the women's game these days is that Serena Williams rarely loses to anyone except herself. And that's only on those rare occasions when she actually does lose.
Williams is the undisputed best in the women's game. Since losing to Samantha Stosur in the 2011 US Open final, she's 118-9. This includes three majors, a year-end championship, an Olympic gold medal and a thunderous return to the world No. 1 ranking.
It is easy to fall under the spell of Williams, who not only has the statistics to burnish her claim to the throne and the historical résumé to place her perhaps as the greatest female player of all time, but also the technical brilliance that allows her to soar above her contemporaries.
But then there's world No. 2 Victoria Azarenka, the only player to have beaten Williams twice this year. Azarenka is the only player on tour who plays Williams as though she expects to win and the one player who could win the US Open and not have it be a complete upset.
Azarenka, who is 36-4 this year and has won three titles, two of which came at Williams' expense, will play her first match of the tournament Tuesday against Germany's Dinah Pfizenmaier, the world No. 99. Azarenka's draw could have her facing Dominika Cibulkova, who beat her at the French Open in 2012, and then Stosur, who beat her earlier this summer in the final at Carlsbad.
Williams dominates tennis the way it is supposed to be dominated, with her serve. She is one of the game's greatest returners. She has outstanding variety and depth on her shots. She doesn't give away bushels of points on double faults, and she is one of the better overall athletes on tour.
Azarenka, on the other hand, has for the past two years alternately fought herself, as well as the competition, to reach the point she is at now. Just last year, in the US Open final, Azarenka served for the match at 5-3 before losing her nerve on key points and ultimately the match. The championship had been at her fingertips.
"I never look back, really," Azarenka said of last year's epic final. "I always look forward. My head doesn't spin all the way back. It will always be a special moment, for sure, because I felt like that whole tournament, that final match, left a big mark on my future career. I still feel that way."
Two weeks ago in the final at Cincinnati, their most recent meeting, Azarenka beat Williams in three sets -- all the more impressive because she lost the first convincingly, and because in the third-set tiebreaker, Williams had the match on her racket, serving at 5-4. It is traditionally this type of moment in which the Williams aura, toughness and intimidation make the difference.
Instead, it was Williams who succumbed to her nerves and Azarenka who held steady and won the match and the title 8-6 in the tiebreaker. There are other players, such as Jelena Jankovic, who don't crumble at the sight of Williams. Azarenka, however, is a better player than Jankovic, and her rivalry with Williams is real.
If the men's game is dependent upon converting second-serve opportunities, the women's game is all about the return, and the woman who can control a point with her serve will be a force. Today, that woman is Williams. But equally impressive is that Azarenka has been able to stay with Williams without being a great server. Entering the US Open, Azarenka has recorded 57 aces in 40 matches, an average of 1.4 per match. But she's double-faulted 183 times, more than four times per match.
Instead, Azarenka's formula has been to pressure serves with defense. She has converted 51.7 percent of her break chances, slightly below Williams' 53 percent.
The problem is Azarenka is holding only 69.6 percent of her service games, which makes her vulnerable to Williams, who holds at 83.7 percent -- a number that would put her very near the top 20 men. The difference in their match in Cincinnati was the number of times Williams was unable to hold serve and keep the return pressure on Azarenka.
Both players are beginning to acknowledge each other as standing in the way of yet another title. Williams is an all-time legend, but she must know Azarenka is the one player she must respect, if not fear.
"It gives you great confidence, but I always think that the new week is the new story," Azarenka said. "You can always take the best out of what happened last week and six months ago, so I will definitely take that into consideration. But the new week is the US Open [and] Serena [is the] No. 1 player in the world, defending champion. We all start from zero here."