What was Serena Williams's first WTA singles title tournament?

Serena Williams won her first WTA singles title at the 1999 Open Gaz de France.

The tournament was played from February 22 to 28, 1999, on indoor hard courts at Stade Pierre de Coubertin in Paris. Serena was unseeded, but she defeated French player Amélie Mauresmo in a tense final, 6–2, 3–6, 7–6(7–4). The victory marked the first singles title of Serena’s professional career.

The achievement came during an especially memorable week for the Williams family. On the same day Serena won in Paris, her sister Venus captured the IGA Superthrift Tennis Classic. Their simultaneous victories made them the first sisters to win WTA tournaments in the same week.

This title is sometimes confused with one of Serena’s later breakthrough victories at a major tournament. The Open Gaz de France was not a Grand Slam event; it was a Tier II tournament on the 1999 WTA Tour. Its importance came from establishing Serena as a WTA singles champion, a status she would build on rapidly with major titles beginning at the 1999 US Open.