Maria Kirilenko and Ana Ivanovic won in straight sets at the Rogers Cup on Tuesday.
Kirilenko cruised past qualifier Petra Martic 6-2, 6-1, and Ivanovic defeated Su-Wei Hsieh 6-1, 6-2 to advance to the second round.
In other matches, American qualifier Lauren Davis edged Svetlana Kuznetsova 3-6, 7-5, 7-5, and Dominika Cibulkova stopped Angelique Kerber 6-7 (0), 6-2, 7-5 in the Rexall Centre at York University.
Cibulkova needed nearly 3 hours to win the match.
''My serve was not working like I was expecting,'' she said. ''But in the end I made it, so I was really happy.''
Jelena Jankovic needed three sets to defeat qualifier Anna Tatishvili 7-6 (6), 4-6, 6-3.
Ekaterina Makarova beat Anastasia Rodionova 6-1, 7-5, and Alize Cornet topped Elena Vesnina 6-3, 6-3.
Later Tuesday, Venus Williams will face Kristen Flipkens in her first match since May, when she lost in the first round of the French Open.
The 33-year-old Williams missed Wimbledon, after...