Despite losing in the US Open quarter-finals, Mauresmo will take over at the top by virtue of Lindsay Davenport’s failure to win her home Grand Slam.
Mauresmo ends the 45-week reign of Belgium’s Justine Henin-Hardenne at the top of the WTA rankings.
Mauresmo is only the 14th woman to become world number one since the rankings began in November 1975.