Amelie Mauresmo became the first French tennis player to be ranked number one in the world on Monday.
Despite having never won a Grand Slam title, the consistent 25-year-old replaced Justine Henin-Hardenne at the pinnacle of the women's rankings after last week's quarter-final appearance at the U.S. Open in New York.
Mauresmo is the first player from France to hit top spot since official rankings were introduced in 1973 for men and 1975 for women.
Prior to official rankings a number of French players have been considered the world's best, from 12-times Grand Slam champion Suzanne Lenglen in the 1920s to Rene Lacoste, Henri Cochet and Jean Borotra in the men's game during the same period.
Mauresmo, winner of three titles this year, pipped former world number one Lindsay Davenport to the top ranking. Davenport would have reclaimed it had she won the Open, but the American lost to eventual champion Svetlana Kuznetsova in the semi-finals.
Russian Kuznetsova jumped from ninth to sixth after her victory over compatriot Anastasia Myskina who climbed one place to second.
Henin-Hardenne, who had been ranked first for 46 weeks since October 2003, was a fourth round loser at the Open and dropped to fourth place three weeks after winning Olympic gold in Athens.
In the men's rankings, Roger Federer surged further ahead at the top after thrashing Lleyton Hewitt to win the U.S. Open.
Winner of the Australian Open and Wimbledon crowns earlier this year, Federer stretched his lead over Andy Roddick at the top of the rankings to 2,990 points.
Roddick, a quarter-finalist in New York, remains second with 3,770 points.
Hewitt moved up two places to number three in the rankings while Federer's beaten semi-final opponent Tim Henman moved up two to number four.
Henman, also a semi-finalist at the French Open this year, equals his highest-ever ranking.
Hewitt's semi-final victim Joachim Johansson, boyfriend of the Australian's sister Jaslyn, also had plenty to smile about after two weeks in New York. The Swede, ranked 150th at the end of last season, vaulted 14 places up the rankings into 16th spot.
Juan Carlos Ferrero's miserable year took another twist as he was bumped out of the top 10, slipping three places to 11.
Runner-up in New York last year, the former world number one lost in the second round of the U.S. Open.