Australia's Lleyton Hewitt became the youngest man in history to finish the year as world number one when he beat Patrick Rafter 7-5, 6-2 at the Masters Cup today.
The US Open champion overtook Brazilian Gustavo Kuerten in the rankings with his third straight win in the season-ending tournament to seal the top ranking at just 20 years and eight months old.
The youngest player before Hewitt to finish the season as No. 1 was American Jimmy Connors, who was 22 years and three months when he achieved the feat in 1974.
"It's an unbelievable feeling," Hewitt said. "For me to do it at age 20 and to do it in Australia, you just couldn't have written a better script".
Only 20 players have reached the No.1 spot since the ranking system was introduced in 1973, with just 12 holding the honour at the end of a season.
The only Australians to top the rankings before Hewitt were John Newcombe and Rafter, although neither finished the year on top.
"He's the best Australia's seen for a long, long time," Rafter said.