PARIS • Novak Djokovic has paid tribute to rivals Roger Federer and Rafael Nadal after he set a new landmark of 311 weeks as world No. 1 on Monday, one week longer than Federer, whose tally of a record 20 Grand Slam titles the Serb is now "devoted" to breaking.
Djokovic, 33, won his 18th Major at the Australian Open last month. With Federer turning 40 in August, the Serb has time on his side. He is a year younger than world No. 2 Nadal, who also has 20 Slam titles.
"When I started in the men's professional tennis world 15 years ago, I had two of the highest challenges, which was to overcome Roger and Rafa," Djokovic said on the BBC.
"Back in 2008, when I won my first Grand Slam, I thought, 'OK, this is now my time. I'm going to be competing with these guys.'
"But then, for three years, I didn't win a Major title and I was losing most of my big matches against them. They made me really sit and realise what I need to do, and how I need to improve.
"They made me the player that I am. Those rivalries are the ones that were the most impactful."
Switzerland's Federer, who returns to action in Doha this week after more than a year out of action to recover from two knee operations, slipped out of the top five to sixth, swopping places with Greece's Stefanos Tsitsipas.
Djokovic reclaimed the top ranking from Spain's Nadal in February last year and finished as year-end world No. 1 for the sixth time, tying the record set by Pete Sampras.
He first became the world's top-ranked player at the age of 24 on July 4, 2011, the day after winning Wimbledon for the first time, beating Nadal in the final.
Few would bet against Djokovic finishing with the most Slams. "The two main goals in tennis are probably the number of Grand Slams won and the number of weeks spent at No. 1," he said. "Now I will devote myself to the second."