The two are set to begin play at the Western & Southern Open in Cincinnati on Wednesday with the No. 1 ranking on the line.
After winning his record-equaling seventh Wimbledon title in July, Roger Federer reclaimed the No. 1 ranking for the first time since 2010 and set a new record for the most weeks as World No. 1. Currently at 11,345 ranking points, Federer finds himself only 75 points ahead of Djokovic (according to the ATP World Tour Website).
Federer is a four-time champion at the Western & Southern Open with victories coming in 2005, 2007, 2009 and 2010. He will begin his campaign for a fifth title against Russian Alex Bogomolov, Jr. on Wednesday. Federer can retain his No. 1 ranking if he reaches the final, regardless of Djokovic's result in the tournament.
Djokovic has never won a title in Cincinatti, finishing as the runner-up in 2008, 2009 and 2011. Djokovic can overtake Federer as the No. 1 if he reaches the final and Federer loses before the quarterfinals. If Federer reaches the quarterfinals or semi-finals, Djokovic must win the title to overtake the Swiss Maestro.