It has become habitual for us to bring up the mention of Big Four while referring to the best players of the current era, however, the 2015 season has been more or less about one man -- Novak Djokovic; he has won three of the four Grand Slams, not to mention the four Masters titles.
Power rests in the hands of this 28-year-old right now, and there is only one man who could truly challenge his existence -- Roger Federer. That being so, we can further trim Big Four to Big Two -- The all-time great Federer and the numero uno Novak Djokovic.
What divides Federer and Djokovic is seven Grand Slams, quite a chasm, seemingly impossible, but we can’t be certain the same time. Federer started slowing down when he was of Djokovic’s age - 28. 16 of his 17 Majors happened before Federer turned 29. In a period between 2011-2015, the Swiss had won only one Grand Slam - Wimbledon (2012).
During the said period, there had been four final appearances as well; three of which happened in the last two years, and he lost all of them to Djokovic. Federer’s worst slump happened in 2013, from which he made an incredible recovery, coming almost close to reclaiming his No:1 spot in 2014, and maintaining that form this season as well. He is in no hurry to hang his racket up for good.