Favorites fared terribly on the opening day at the WTA portion of the Rogers Cup, a "Premier 5"-level tournament in Toronto, Canada. Seeded players amassing a record of 1-4 on Monday, while qualifiers found far more success, going 5-2.
Here's a look at the ten singles matches in the books after Day 1 of main draw action in Canada's largest city.
Galina Voskoboeva (Kazakhstan) [Q] def. Marion Bartoli (France)  6-3, 6-3 -- The most stunning upset of all was the first of the day, as struggling qualifier Galina Voskoboeva knocked out recent Stanford finalist Marion Bartoli 6-3, 6-3. Voskoboeva, a Russian who was paid by Kazakhstan to play for them instead, has been playing well this year since adding former player Alina Jidkova as her coach. Bartoli didn't play especially badly, simply overmatched by the quick, deep balls of Voskoboeva, who is a top 20-caliber talent when playing her best tennis. The Bartoli scalp is Voskoboeva's first career win over a top-10 player.
Samantha Stosur (Australia)  def. Ayumi Morita (Japan) 4-6, 6-2, 6-3 -- The lone victorious seed Monday, Sam Stosur fought through a tough win over Ayumi Morita. Morita, who beat Ana Ivanovic en route to making the quarterfinals in Stanford, was able to jump on top of Stosur early in points early on, before Stosur found her range. Stosur fell out of the top 10 for the first time in 16 months this week, bumped by fast rising German Andrea Petkovic. Stosur did not play in Canada or Cincinnati last year, so the opportunity is there for her to make up a lot of points in the coming weeks.
Simona Halep (Romania) [Q] def. Svetlana Kuznetsova (Russia)  4-6, 6-4, 6-3 -- Perhaps more than any multiple Grand Slam winner in history, Svetlana Kuznetsova has the ability to come off the rails completely. Kuznetsova started well against the talented Romanian baseliner, but her lack of match toughness and focus allowed Halep to take control early in the second set and never look back. Kuznetsova made the semifinals of the Rogers Cup last year, so this early loss (combined with her not attempting to defend her title in San Diego last week) will see her fall significantly in the rankings yet again. This was Halep's first career victory over a top 20 player.
María José Martínez Sánchez (Spain) [Q] def. Anastasia Pavlyuchenkova (Russia)  3-6, 6-4, 6-1 -- In a battle of extremely long names, talented all-court player Maria Jose Martinez Sanchez upset Anastasia Pavlyuchenkova in a three-set match that was very tight until the final set. Like Kuznetsova, Pavlyuchenkova also has to worry about defending points in the coming weeks, with a semifinal run in Cincinnati last year and her points from her 2010 title in Istanbul indefensible due to the tournament being taken off the calendar. Should be interesting to see how she responds to the pressure next week in Ohio.
Julia Goerges (Germany) def. Jelena Jankovic (Serbia)  6-1, 6-3 -- A shockingly uncompetitive effort from Jelena Jankovic, who was the No. 1 seed at this tournament only a year ago. Her year has been extremely disappointing, to say the least, with back-to-back first round losses at Wimbledon and now Toronto. The win snaps a four-match losing streak for Goerges, who had a strong season on clay but had been unable to carry her momentum onto other surfaces. The road gets tougher from here for Goerges, who could play Serena Williams in the second round.
Ekaterina Makarova (Russia) def. Rebecca Marino (Canada) 7-6(6), 6-4 -- A tough loss for the extremely grounded native daughter Rebecca Marino, who was the only Canadian player competing in either the men's or women's Rogers Cup who had entered the tournament on the strength of her own ranking (due to the injury-caused absence of Milos Raonic). A Marino win would have set up a fun rematch of her thrilling Australian Open second round match against Francesca Schiavone, which Schiavone won 9-7 in the third set. Wild cards Aleksandra Wozniak (who just won a challenger in Vancouver), Stephanie Dubois, and Genie Bouchard remain in the draw.
Nadia Petrova (Russia) def. Jarmila Gajdosova (Australia) 6-1, 6-2 -- A lopsided win for Petrova over the talented but streaky Gajdosova, knocking off the Slovak-turned Aussie in only 53 minutes. On the back of her title at the Citi Open in College Park two weeks ago, Petrova is currently carrying the second longest win-streak in tennis at six, second only to Wimbledon champion Petra Kvitova's seven. With how well Petrova is playing, her second round match against compatriot and No. 3 seed Vera Zvonareva could bring a surprise.
Lucie Safarova (Czech Republic) def. Polona Hercog (Slovenia) [Q] 6-3, 4-6, 6-3 --A nice win for Lucie Safarova, who is rumored to have recently broken up with long-time boyfriend Tomas Berdych. Hercog had an incredible post-Wimbledon run on European clay in July, winning her first WTA title in Bastad, Sweden and making the final in Palermo, Italy. Safarova next faces Simona Halep, which is a nice opportunity for both to make it to the third round of a tournament as large as this.
Greta Arn (Hungary) [Q] def. Klara Zakopalova (Czech Republic) 6-3, 6-1 -- 32-year-old Greta Arn is one of the quieter members of the veterans' movement currently running through tennis, but this was a big win for the Hungarian qualifier. Klara Zakopalova hadn't played a hard court match since March, which likely contributed to the lopsidedness of this result.
Zheng Jie (China) [Q] def. Alberta Brianti (ITA) [Q] 6-2, 6-1 -- The struggling Zheng Jie, who has fallen well outside the top 50 since the beginning of the year, definitely needed a win here to get her season back on track. That win is unlikely to be followed with another in the next round, however, as Zheng is set to face No. 2 seed Kim Clijsters in the second round. But with Clijsters' recent injury woes, Zheng might at least be able to make it interesting.
Stay tuned to SB Nation's coverage of the 2011 US Open Series at SBNation.com as well as on Twitter, @DailyForehand .