Two-time champion Simona Halep beat Coco Gauff 6-4, 7-6 (2) to reach the National Bank Open semi-finals.

Halep, the 30-year-old from Romania, won the event in Montreal in 2016 and 2018. She will face seventh-seeded Jessica Pegula, a 6-3, 6-3 winner over Yulia Putintseva of Kazakhstan.