Top-ranked Serena Williams stumbled in the Rogers Cup semifinals Saturday night, falling 6-3, 5-7, 4-6 to Swiss teenager Belinda Bencic.
The winner of the first three Grand Slam events of the season, the 33-year-old Williams lost for only the second time in 45 matches this season. She won titles in Toronto titles in 2001, 2011 and 2013.
The 18-year-old Bencic, ranked 20th, has knocked off three seeded players en route to her first career appearance in a Premier-5 Level event. She opened with a victory over Canada's Eugenie Bouchard and followed with wins over fourth-seeded Caroline Wozniacki, Sabine Lisicki and fifth-seeded Ana Ivanovic.
In the other semifinal, second-ranked Simona Halep of Romania beat Sara Errani of Italy 6-4, 6-4.
In the doubles semfinals, fourth-seeded Caroline Garcia of France and Katarina Srebotnik of Slovenia beat top-seeded Martina Hingis of Switzerland and Sania Mirza of India, 6-3, 6-2; and third-seeded Bethanie Mattek-Sands of the United States and Lucie Safarova of the Czech Republic topped Kristina Mladenovic of France and Karolina Pliskova of the Czech Republic 6-4, 7-6 (5).