Saturday, 11 August 2012:

Reigning US Open champion Sam Stosur suffered a blow ahead of her title defence in New York later this month when she lost to Lucie Safarova in the third round of the Rogers Cup in Montreal on Friday.

Just over two weeks from the start of the last grand slam of the year, the Australian fourth seed went down 7-6 (11-9) 7-6 (7-5) to Safarova.

Both players broke the other's serve in the opening set but were unable to strike again, leaving Czech 16th seed Safarova to grab first-set honours after a marathon tiebreak.

Stosur, who lost to American Serena Williams in last year's Montreal final, had big problems with her second serve, winning only 37 per cent of the points on her second delivery in the entire match.

Although Stosur more than matched her opponent from the back of the court, Safarova would ultimately make her pay for her failure to land more potent second serves.

Two breaks each in the second set meant another tiebreak was needed to separate them, and Safarova held her nerve to claim victory in two hours and ten minutes.

Meanwhile, fifth-seed Petra Kvitova of the Czech Republic reached the quarter-finals with a 6-1 6-1 defeat of France's Marion Bartoli.

Sixth-seeded German Angelique Kerber stopped Ekaterina Makarova of Russia 6-3 6-3 and Caroline Wozniacki of Denmark ousted Kiki Bertens 7-5 6-1.

Canadian wildcard Aleksandra Wozniak led American Christina McHale 7-6 (7-5) 5-2 when play was called off for the day.

World No.2 Maria Sharapova withdrew on Friday from next week's ATP-WTA Cincinnati event with the same stomach virus that has kept her from this week's tournament in Montreal.

The Russian Olympic silver medallist reported on her website that she would not play any events before the US Open begins on August 27.

World No.1 Victoria Azarenka also pulled out of the WTA Rogers Cup due to a knee injury.

The Belarussian player said she has been over-compensating for the injured knee due to an intense playing schedule and has yet to recover energy after the London Olympics.

AAP