Montreal - British qualifier Heather Watson has caused an upset at the Rogers Cup on Wednesday by beating 12th-ranked Dominika Cibulkova 6-2, 6-7 (3), 7-6 (5) in the second round.
Watson let a 5-2 lead slip away in the third set before rallying.
The 22-year-old will face No. 11 Victoria Azarenka in the third round on Thursday.
No. 13 Caroline Wozniacki cruised past Klara Koukalova 6-1, 6-2 and will meet American qualifier Shelby Rogers in the third round. Rogers had upset eighth-ranked Canadian Eugenie Bouchard 6-0, 2-6, 6-0 on Tuesday.
Germany's Angelique Kerber ousted Caroline Garcia of France 6-4, 6-1.
Top-ranked Serena Williams will face No. 21 Samantha Stosur later Wednesday.
Results on Wednesday from the third day of the WTA Montreal tournament (x denotes seed):
Caroline Wozniacki (DEN x11) bt Klara Koukalova (CZE) 6-1, 6-2
Carla Suarez (ESP x14) bt Karolna Plskova (CZE) 6-1, 3-6, 6-3
Angelique Kerber (GER x6) bt Caroline Garcia (FRA) 6-4, 6-1
Heather Watson (GBR) bt Dominika Cibulkova (SVK x10) 6-2, 6-7 (3/7), 7-6 (7/5)
Ekaterina Makarova (RUS) bt Elena Vesnina (RUS) 6-3, 6-2