By A Mystery Man Writer
Roger Federer was left stung by Novak Djokovic's comeback in their five-set US Open semi-final
US Open: Novak Djokovic and Roger Federer eye the crown, while Serena Williams looms as one to beat - ABC News
Why Novak Djokovic Performs Under Pressure, Earning 23rd Grand Slam Title at French Open
Sport, Us/sport
Novak Djokovic vs Roger Federer head to head at the US Open 2015 - Sports Illustrated
Which are the most devastating losses in careers of Federer, Nadal and Djokovic? - Quora
To Lose Against Someone Like That Is Disappointing: When Roger Federer Was Infuriated by Novak Djokovic at US Open - The SportsRush
Djokovic Upsets Federer to Gain Men's Final - The New York Times
Federer, Nadal join Djokovic in Indian Wells quarterfinals
US Open 2011: Roger Federer struggles to accept Novak Djokovic defeat, US Open 2011
Roger Federer beats Novak Djokovic in Dubai Championship semi-finals - ABC News
Novak Djokovic - Wikipedia