• Roger Federer (R) of Switzerland and Novak Djokovic of Serbia

Roger Federer (R) of Switzerland and Novak Djokovic of Serbia (Photo : REUTERS/Ahmed Jadallah)

Novak Djokovic believes he's playing in a much better form than his epic run in 2011, where he bagged three Grand Slam Championships and became the world's top player for the first time in his career. However, the Serb never forgot that it was also that year that he finally solved the puzzle of Roger Federer.

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Djokovic was once again in his calm, confident self as he talked to reporters before kicking off his defense at the Rome Masters. According to the 27-year old Serb, he thinks he's playing at the peak of his abilities right now, even better than his legendary run four years ago when he won the Australian, Wimbledon and US Open.

Djokovic, who became the first ATP player to win the first Masters 1000 tournament of any calendar season, said his 2015 version is stronger both physically and mentally and his gluten-free diet has to be credited for that.

Still, the 8-time Grand Slam winner also added that his 2011 campaign run holds a 'special place in his heart' because it was the point when he finally solved one of the greatest jigsaw puzzles in tennis: how to beat Federer in big tournaments.

Djokovic said via World Tennis USA:

"2011 has been the season where I have become World No.1, the season where I beat Roger Federer in five sets at the US Open, something no one had ever been able to do before. Because of that that year holds a special place in my heart, that's for sure, it has been a year full of great emotions. But today I feel stronger, not just physically but mostly mentally, also because I am happier, more serene. The gluten-free diet really did help me in feeling better".

Federer dominated his head-to-head encounter with Djokovic prior to 2011. However, the Serb stepped up to the plate and emerged as one of the greatest tennis players in this era. Now, Djokovic is standing tall over the rest of his rivals, trying to pull off something that even the great Federer had hard time accomplishing - winning all four Grand Slam titles in a calendar year.