Juan Martin Del Potro celebrates win over Rafael Nadal in Shanghai.
The 2013 tennis season may be winding down, but players continue to jockey for position in the rankings.
Some, like Juan Martin Del Potro and Angelique Kerber, capitalized on late-season surges to qualify for the year-end championships.
Others, like teen sensations Madison Keys and Eugenie Bouchard, are gaining ground and experience.
This list is not about the battle for No. 1. Some of the players listed here are ranked outside of the Top 20. This is about players experiencing late-season success. These players have taken advantage of the post-U.S. Open schedule to end the year on a high note.
Kerber has bounced back from a lackluster summer.
She seemed to find her form on the Asian swing of the tour. On Oct. 13, Kerber defeated Ana Ivanovic in Linz to capture her third title this year. She also earned the final spot in the WTA Championships.
She's won 11 of her last 13 matches. Back in the Top 10, Kerber could continue moving up the rankings with a solid performance in the championships.
John Isner in Shanghai 2013
John Isner is quietly putting together a nice season. Already ranked higher than he's been since January, Isner is by far the highest-ranked American male.
Last week Isner jumped three spots from No. 16 to to No. 13. Yet, you get the sense that tennis fans are not convinced Isner is or ever will be the real deal. An American male inching closer to the Top 10 without making noise means Isner has much work to do to convert nonbelievers.
Petra Kvitova has won eight of her last nine matches, including the Pan Pacific title. Kvitova also qualified for the year-end championships where she could continue her late-season run.
Bouchard finished 2012 ranked No. 144. She is the highest-ranked teen on tour. The Canadian's slow but steady move up the rankings is reminiscent of Sloane Stephens' ascent into stardom.
Juan Martin Del Potro against Novak Djokovic in Shanghai
Juan Martin Del Potro lost to Novak Djokovic in the final in Shanghai, but the Argentinean secured a spot for himself in the ATP Championships in London.
Del Potro, ranked No. 5, has had a steady move up the rankings post-U.S. Open. His win over Nadal in Shanghai makes him perhaps the most dangerous man on tour outside of the Djokovic, Nadal and Andy Murray trio.
Madison Keys, like Bouchard, is a teen on a mission. She is ranked No. 36, just four spots behind Bouchard.
However, Keys is a year younger than her Canadian counterpart. She finished 2012 ranked No. 149. Keys and Bouchard are ranked higher than No. 46 Laura Robson, the British teen who arrived on tour with more hype and gets far more press.
Gael Monfils in Shanghai
The win against Federer was a good start.