• Novak Djokovic

Novak Djokovic (Photo : Getty Images)

Novak Djokovic shared one of the keys to successfully own the No. 1 spot in the ATP world rankings, which the Serb has been keeping hold of since June 2014.

During a post-match interview following his 7-5 7-5 victory over Stephane Robert in the second round of the Italian Open, Djokovic shared the secret behind his dominant run in the past two years.

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"If you really want to play at the top and if you want to be a candidate for a top spot in the world, you need to be healthy. In order to be healthy, you need to really be devoted, I mean, for several hours a day to your body," Djokovic said, reports Tennis World USA.

Djokovic has not had any significant injuries in his career, and has avoided them well during his dominant run in the sport. The Serb's most recent setback was an eye infection suffered during the Dubai Tennis Championships in February, but has been physically healthy ever since, which translated to back-to-back titles in Indian Wells and Miami before copping up another win in Madrid.

At the Italian Open, there are certainly no indications of injury or any concerns on Djokovic's health that may spoil his bid for a second-straight title in the clay-season. But as the French Open approaches, he must do all he can to stay healthy and in-form to win a title in Paris, something Nole has yet to achieve in his career.

Meanwhile, Djokovic faces career rival Rafael Nadal in the quarterfinals of the Italian Open at the Foro Italico in Rome. The 28-year-old Djokovic overcame a rusty first set to defeat Thomaz Bellucci 0-6 6-3 6-2, while Nadal also had some first set troubles against Australia's Nick Kyrgios before winning the match 6-7(3) 6-2 6-4.

"I've played him in Rome several times... I have watched his match," Djokovic said of Nadal. "I'm going to try to get myself ready. I'm hoping I can start better than I did today."

Djokovic has won his last six matches against Nadal, most recently in the semifinal round of Indian Wells in March. If Djokovic wins, he could face either Dominic Thiem or Kei Nishikori in the semifinal stage.