Portugal Colonial - On top of the world: Three tennis rankings landmarks

The 35-year-old winner of 22 Grand Slams titles is starting his 378th week in pole position, edging ahead of Steffi Graf who was on top of the women's rankings for 377 weeks in her career.

"It's surreal in a way to be that many weeks world number one, to match Steffi Graf, who is one of the all-time greats of our sport, both men and women," said Djokovic, whose first spell at the top began in July 2011 after his maiden Wimbledon triumph.

Here, AFP Sport looks at three rankings landmarks:

- Pat Rafter: Two Slams, one week at number one -

Australia's Pat Rafter served-and-volleyed his way to the 1997 and 1998 US Opens, two of his 11 career titles.

Rafter was, however, plagued by shoulder trouble all his career and retired in 2001, aged just 29 with two heartbreaking defeats in Wimbledon finals unwanted memories.

Rafter was world number one for just a week from July 26, 1999, the first Australian man to reach the peak since John Newcombe in 1971.

He took top spot from Andre Agassi and then quickly surrendered it to Pete Sampras.

Rafter remains the only player since rankings began in the 1970s to spend just one week at number one. Next on the list are Evonne Goolagong and Carlos Moya who spent two weeks each at the summit.

"I always joke with the players. They say, 'Congratulations, mate, you made No. 1.' I say, 'Yeah, one week.' They say, 'At least you bloody got it. At least you can say you got there'."

- Rafael Nadal: 18-year top 10 veteran -

Rafael Nadal first broke into the world top 10 on April 25th, 2005 -- and the 22-time major winner has been there ever since.

He was just 18 at the time; now he is 36.

Nadal has also spent 209 of those weeks as number one, first reaching the summit in August 2008.

The Spaniard's spell in the top 10 has stretched over 900 consecutive weeks, a feat that not even Novak Djokovic or the now-retired Roger Federer can boast.

Only Martina Navratilova, with 1,000 weeks in a row inside the WTA top 10, can better Nadal's astonishing longevity.

Navratilova was ranked in the top 10 from the first computerised ranking on November 3, 1975 until December 26, 1994.

- Steffi Graf: Women's trailblazer -

Djokovic was barely three months old when Graf became women's world number one for the first time in August 1987.

The German star was just 18 and would remain on top of the pile in her first spell for 186 weeks.

It was a landmark moment in the women's game as it came the day after Graf had won the first of her 22 majors at the French Open.

She was also the first woman outside of Martina Navratilova, who had held top spot for 322 weeks, and Tracy Austin in seven years to ascend to the number one ranking.

Graf, who won 107 career titles, retired in August 1999.

L.Mesquita--PC