Martina Hingis is a professional tennis player who was the singles world No. 1.
Martina Hingis ( born 30 September 1980 ) is a Czechoslovak-born Swiss professional tennis player who spent a total of 209 weeks as the singles world No. 1 . Hingis set a series of `` youngest-ever '' records during the 1990s , including youngest-ever Grand Slam champion and youngest-ever world No. 1 .