While the Rolex Masters tennis tournament continues, many top stars are trying hard in their matches in Shanghai to secure prestigious spots in the Barclays ATP World Tour Finals to be staged at the O2 arena in London for a fifth straight year. Like every year, only the best eight singles players and best eight doubles teams of the season qualify for the famed World Tour Finals. While Novak Djokovic and Roger Federer entered the quarterfinals with some hiccups,