Despite exiting the China Open in the first round, Victoria Azarenka will be delighted with maintaining momentum a year after a breakout 2012 season that she finished as world No. 1. Now the second-ranked woman in the world, Azarenka reached the semifinals or better at three majors this year while defending her Australian Open title.  Moreover, she scored Premier Five titles in Doha and Cincinnati at the expense of Serena Williams, a step forward in her evolving rivalry with the current No. 1.

But this fall has featured some of Azarenka’s least impressive hard-court tennis since her breakthrough.  The world No. 2 suffered opening-round losses to Venus Williams and Andrea Petkovic in Tokyo and Beijing, struggling with illness and a wayward serve. Perhaps the time has arrived for Azarenka to take a longer break from the game, even if it means missing the WTA year-end championships in Istanbul.

Unlike other women in the top 20, this fiery competitor’s mental resilience ranks among her strongest weapons. Azarenka’s performance in the US Open final against Serena Williams outlined just how far the determined young Belarussian has come since her days as a promising but immature dark horse.

After losing the first set in a tough battle, a 2011 Azarenka would have wilted under the bright lights of Arthur Ashe. But the 2013 version did not. Azarenka bounced back, mentally and physically outlasting Williams in the second set before the world No. 1 recovered to defend her title in an epic encounter.

Despite her eventual loss that day, US Open commentators marveled at Azarenka’s mental strength during the second set and the way that Azarenka held herself together to compete. On the other hand,  one of the most questionable areas of Azarenka’s game remains her physical fitness. This is the area most likely to prevent her from overtaking (or outlasting) an in-form Serena at the top. Signs of her uncertain physical fitness emerged earlier this season with withdrawals from the elite North American tournaments at Indian Wells and Miami. Battered by a knee injury at Wimbledon, her body betrayed her again in Tokyo and Beijing,

“If I'm going to be doing it again, I probably should have taken a longer break [between tournaments] and just prepared myself,” said a disappointed Azarenka to the AFP after this week's loss to Petkovic.

“I don't feel like I was ready to play,” she continued. “It's just my mistake for not paying much attention after the US Open how I managed my time and how I managed my health.”

It is nearly certain that Azarenka will finish the year at No. 2 in the rankings with leading rival Maria Sharapova absent from the Asian swing and the fourth-ranked Agnieszka Radwanska delivering inconsistent results. Even with the WTA year-end championships on the horizon, Azarenka’s physical vulnerability might cause her to consider shortening a very successful season prematurely to be fit for another Australian Open title defense.