This was the Belgian’s second win over Osaka in three meetings this year. Mertens won their clash in Indian Wells in March in straight sets but lost in S-Hertogenbosh on grass in June, also in straight sets. Overall, Osaka leads their head-to-head 4-3 after this latest result.

In the previous round of the Rogers Cup, the Belgian won against American qualifier Katie Volynets (6-3, 6-1).

Osaka, ranked No 95, won against Tunisian Ons Jabeur, the No 9 seed (6-3, 6-1) during the first round of the Rogers Cup.

Toronto WTA 1000, other second-round results (Aviva Centre, hard, USD 3.211.715, most recent results first):

• Victoria Azarenka (12) beat Greet Minnen (Q): 3-6, 7-5, 6-1
• Aryna Sabalenka (2) beat Yue Yuan: 6-2, 6-2
• Jelena Ostapenko (4) beat Paula Badosa: 3-6, 7-6 (3), 6-2
• Amanda Anisimova beat Daria Kasatkina (5): 6-4, 6-3
• Katie Boulter beat Beatriz Haddad Maia (13): 1-1 ret.
• Peyton Stearns beat Madison Keys (7): 3-6, 7-5, 3-0 ret.
• Ashlyn Krueger (Q) beat Leylah Fernandez (15): 6-4, 6-2
• Emma Navarro (8) beat Magda Linette: 6-2, 6-4
• Taylor Townsend (LL) beat Marina Stakusic (WC): 6-0, 6-2
• Liudmila Samsonova beat Moyuka Uchijima (Q): 6-4, 6-2
• Coco Gauff (1) beat Yafan Wang (Q): 6-4, 6-4
• Anna Kalinskaya (10) beat Lesia Tsurenko: 6-2, 6-2
• Marta Kostyuk (11) beat Elina Svitolina: 6-2, 2-6, 6-2
• Diana Shnaider (14) beat Magdalena Frech: 2-6, 6-3, 7-6 (5)
• Jessica Pegula (3) beat Karolina Pliskova: 7-5, 6-4