American Amanda Anisimova upset two-time reigning Australian Open champion Aryna Sabalenka 6-4, 6-2 on Saturday to reach the semifinals of the WTA Toronto Masters.
Anisimova, into her first Masters semifinal, advanced to a Sunday showdown against US eighth seed Emma Navarro, who eliminated fellow American lucky loser Taylor Townsend 6-3, 7-6 (7/5).
Anisimova, 22, will try to reach her fourth career WTA final and first since winning at Melbourne in January 2022.
She also won at Bogota in 2019 after losing her first career WTA final at the 2018 Japan Open.
World number 15 Navarro, 23, won her only prior WTA final in January at Hobart.
"She's a player who is definitely on fire right now. She's playing some great tennis," Anisimova said of Navarro. "I'm sure it will be a tough match."
World No 3 Sabalenka was broken in the 10th game to drop the first set, netting a backhand to surrender to set then slamming her racquet to the court in frustration.
After an early exchange of breaks in the second set, Sabalenka netted a backhand to give 132nd-ranked Anisimova a break and a 4-2 edge.
Anisimova, who has not lost a set this week, then won the last eight points – holding at love for a 5-2 lead and breaking at love to complete the upset after 86 minutes when Sabalenka double faulted.
"She's an amazing player, so it's always really tough playing against her," Anisimova said of Sabalenka.
Third-seeded defending champion Jessica Pegula advanced by eliminating fellow American Peyton Stearns 6-4, 7-5 in 89 minutes.
Pegula stormed back after falling behind 5-2 in the second set.
"I just reminded myself of what I needed to focus on," Pegula said. "Even though it was 5-2, I knew there was always still a chance I could come back, especially having break points earlier on in the set as well and that seemed to work for me."
Pegula reached her fourth consecutive Canadian Masters semifinal, matching Gabriela Sabatini and Simona Halep one off the record held by Monica Seles.
She will next face Russian 14th seed Diana Shnaider, who upset sixth-seeded compatriot and 2023 Canada runner-up Liudmila Samsonova 4-6, 6-1, 6-4.
Shnaider, who ousted US top seed and reigning US Open champion Coco Gauff on Friday, swatted a forehand down the line winner to break for a 4-3 lead in the final set and held from there to advance.
Shnaider, ranked 24th, seeks her fourth WTA title of the year after Thailand, Bad Homburg and Budapest.