Bizarrely, Federer will face Djokovic and Ferrer will face Nadal in their very first round-robin matches on Tuesday when the year-end championships at the ATP World Tour Finals start in London on Tuesday. Federer, Djokovic, Juan Martin del Potro and Richard Gasquet are in one group with Nadal, Ferrer, Tomas Berdych and Stanislas Wawrinka in the other.
If Djokovic wins the Paris Masters and defends his 2012 ATP Year-End Championship and Nadal failes to win a round-robin match there then the Serb will be #1 for 2013, which is a very unlikely result. Nadal deserves to end 2013 with his 71-6 record for the year and 10 titles, including two majors (2013 French Open and 2013 US Open).
Djokovic leads Ferrer 10-5 in their overall head-to-head and is playing some of his best tennis all year, having won 16 matches in a row since losing the final of the US Open to Nadal in September.
MadProfessah's prediction: Djokovic