Serena Williams solidified her No. 1 ranking by defending her title at the 2013 WTA Championships. Her seemingly insurmountable 5,046 points lead in the WTA rankings reflects the gap between her game and that of the rest in the field.
Williams is clearly the top player. However, there is some serious shifting in the Power Rankings amongst the rest of the Top 10.
Since the U.S. Open, we've seen Li Na, Jelena Jankovic and Petra Kvitova surge. Meanwhile, Maria Sharapova, absent with an injury, became a none factor. Victoria Azarenka, who entered the year ranked No. 1, is mired in a slump.
Most of the names in the Top 10 remain the same. But the Power Rankings have changed.
WTA Ranking: 10
Power Ranking Reason: Caroline Wozniacki comes in at No. 10 after a productive fall season. If not for the Linz tournament allowing Angelique Kerber a last-minute wildcard, Wozniacki may have made it back to the WTA Championships.
WTA Rankings: No. 7
Power Ranking Reason: Despite spending most of the year in the Top Five, Sara Errani comes in at No. 9 in the Power Rankings. A consistent counter puncher who plays with finesse, Errani is no match against heavy hitters.
Her deceptive style of play caught many players off guard last year when she rocketed up the rankings. Now her game has been studied and dissected. Her serve is still among the weakest on tour. Still half of the No. 1 doubles team, Errani seems to have peaked in singles.
WTA Rankings: No. 9
Power Ranking Reason: Angelique Kerber found her form this fall. She entered Tokyo, Beijing and Linz to boost her chances of qualifying for the WTA Championships. Although she had just one win in the championships, over Agnieszka Radwanska, Kerber looked sharp in a three-set loss to Kvitova.
WTA Ranking: No. 5
Power Ranking Reason: Similar to Sara Errani, Agnieszka Radwanska plays with enough consistency and accuracy to stay in the Top 10. When her opponents falter, she's there to hit that extra shot for a winner.
Also like Errani, Radwanska may have peaked. She seems less steady. In 2012, she upset Sharapova in Miami and forced Serena Williams to three sets at Wimbledon.
Lately, she's struggled against top players. She left Istanbul 0-3. Despite her ranking, Radwanska is not playing top-five tennis.
WTA Ranking: No. 8
Power Ranking Reason: Jelena Jankovic raised eyebrows at the WTA Championships when she accused Serena Williams of faking injuries when trailing in tournaments. Jankovic's pension for drama and distraction could be the only thing keeping her from returning to the top five.
Jankovic upset No. 2 Azarenka and took a set off Williams at the tournament. With her brother as coach, Jankovic appears to be easing back into top tier status.
WTA Ranking: No. 4
Power Ranking Reason: Due to injuries, Sharapova hasn't played since she lost a first-round match to Sloane Stephens in Cincinnati this summer. She's only won one match since losing to Serena Williams in the final of the French Open in June.
Despite missing the U.S. Open and the entire fall season, Sharapova remains in the Top Five because of her stellar performance earlier this year.
It's unclear what type of player Sharapova will be upon her return. Regardless, with four Grand Slam titles and the No. 4 ranking, no way does she belong any lower than fifth in the Power Rankings.
WTA Ranking: No. 6
Power Ranking Reason: Petra Kvitova is one of the five women in the Top 10 who has won a Grand Slam title. Kvitova entered the tournament on a roll. She had won nine of her last ten matches, including the title at the Pan Pacific Open.
She's only 23, but it seems like fans have been waiting forever to see Kvitova live up to the expectations that arose from her 2011 Wimbledon win.
WTA Ranking: No. 2
Power Ranking Reason: Victoria Azarenka is in a serious funk. She's lost five of her last six matches. It's hard to say if her problem is mental, physical or a combination of the two. She certainly seems to have lost some fire. Azarenka will have to regroup if she wants to defend her Australian Open title.
WTA Ranking: No. 3
Power Ranking Reason: Since taking on Carlos Rodriguez as coach, Li Na has incorporated the serve-and-volley into her game. Her more aggressive style of play left Serena Williams bewildered in the first set of the WTA Championships final.
Rodriguez, who coached Justin Henin, understands better than any coach that you can't just out-hit Williams. Rodriguez has tried to help Li outsmart Williams. He has her moving forward and dictating play instead of reacting to Williams. It worked well in the first set of the WTA championships. But alas, Li lost belief and the unforced errors crept in.
Even if Li can't get over her jitters against Williams, she'll be able to manage everyone else on tour. She went 3-1 at the WTA Championships. Right now only Williams is playing better.
WTA Ranking: No. 1
Power Ranking Reason: Duh. There's simply not enough superlatives to describe the record-breaking year Serena Williams is having. She won a personal best 11 titles. She became the oldest woman to reach No. 1. Her 78-4 record gives her a .951 winning percentage this year.
Williams earned $12.3 million in prize money. That broke the previous single-season record by nearly $5 million.
Her next big challenge is the Australian Open and a bid to tie Martina Navratilova and Chris Evert with 18 Grand Slam titles. For the first time in years, the season ends with the No. 1 player and the player with the No. 1 ranking one in the same.