TORONTO - Canada's marquee women's tennis tournament lost the last of its Canadian contingent in women's singles on a day that saw its defending champion ousted as well.

Canadians Aleksandra Wozniak and Stephanie Dubois were both dispatched in the second round of the Rogers Cup on Wednesday, continuing a frustrating streak that hasn't seen a Canadian advance to the third round in Toronto since Helen Kelesi in 1991.

But the biggest upset of the day was the ejection of top-ranked Caroline Wozniacki of Denmark, who was shocked by Roberta Vinci 6-4, 7-5 on a day plagued by blustery winds at Rexall Centre.

Wozniacki, who has won a WTA-leading five titles this year, was up 5-1 in the second set and looking to rally from a set down. However, the No. 22-ranked Italian stormed back with three break points to complete the upset.

Wozniacki had a bye in the first round and never really got going against Vinci, sending her return long on match point. Wozniacki also hit returns long twice at the first set point to give Vinci a lead she would not relinquish.

"I would have liked to have won that one and especially after leading 5-1 in the second," Wozniacki said. "It's not fun to lose this, but there's nothing really I can do about it now, just practise, and try to do better."

Wozniacki was the latest in a list of top-seeded players to bow out early. Second-seeded Kim Clijsters withdrew Tuesday due to an abdominal injury, while former world No. 1 Jelena Jankovic and the tournament's No. 9 seed Marion Bartoli were dispatched in their opening matches.

Wozniak, from Blainville, Que., lost to No. 10 seed Samantha Stosur 6-3, 6-4, while No. 4 Victoria Azarenka of Belarus made quick work of Dubois, beating the Laval, Que., native 6-0, 6-0.

Fifth-seeded Maria Sharapova and former No. 1 Serena Williams both survived scares to advance.

Sharapova edged 19-year-old Bojana Jovanovski of Serbia 6-1, 7-5 in a chilly evening match. Sharapova's serve abandoned her in a second set that saw her commit five double faults. The three-time Grand Slam champion finally sealed the victory when Jovanovski fired a return long.

Williams battled through a tough second set en route to a 6-1, 7-6 (7) win against Julia Goerges.

The former world No. 1 and 13-time Grand Slam champion from the U.S. used her intimidating serve, which topped out at 195 kilometres per hour, to roll through her first set before the 20th-ranked German fought back in the second.

Windy conditions, with gusts of 35 km/h that swirled around the court, wreaked havoc with play all day, and forced the match between Ana Ivanovic and Iveta Benesova to be moved from centre court after a fallen light left broken glass on the playing surface.

The blustery wind was obvious in Wozniacki's serve in the first set, as the ball repeatedly floated away when she tossed it above her. She double-faulted seven times in the match.

"It was very difficult at first with the wind," Wozniacki said. "Especially when you threw it up. It was going everywhere, so definitely that didn't make it easy. It was blowing in different directions, but it's the same for both players."

It will be Vinci's first appearance in the third round of the Rogers Cup in her third visit to the tournament. She has wins this year in Barcelona, Budapest and Hertogenbosch.

Vinci ranked this upset as a definite career highlight.

"This is the best victory in my life," the 28-year-old said emphatically. "I was 5-1 down but I knew that I can win the set because it was a lot of wind, so some mistakes.

"I tried to stay focused and play aggressive. That's it, this is the key why I won the set."

Wozniak has never made it past the second round in eight tries at the Rogers Cup.

"Well, it's disappointing," Wozniak said. "You play at home and you want to do so well. But I thought it was a good match, and I had a really tough opponent today."

Wozniak clawed back to 5-3 in the first set with beautiful cross-court backhand and an ace, but gave up any chance to rally when she returned the Australian's serve long to lose the set.

The Canadian got some help winning the first game of the second set when the wind took hold of a high lob and carried it inches over Stosur's side of the net. The 23-year-old could only smile and shrug as her many supporters cheered her on.

"Obviously the conditions were pretty tough today," Wozniak said. "When you step on the court, you've got to be ready to deal with whatever comes in front of you, your opponent or the sun or the wind, and yeah, they were pretty difficult, but I tried my best."

Williams joined the chorus of complaints about the wind.

"I thought (Goerges) played really well and really smart, the conditions were extremely tough. I thought that she had to change up her game and I had to adjust to that," Williams said. "It was just so much wind out there so it was a little difficult, but we were in the same circumstances so that's what I tried to think of. But she played really well."

Williams giggled when asked if her powerful serve gives her an advantage in the wind.

"I had to hit it softer today because it was so windy, I had to take pace off my ball," said the U.S. star. "You're not a tennis player? Yeah, I could tell. If you hit it too hard the ball is going to totally fly the harder you hit."

Serbia's Ivanovic eased into the third round with a 6-3, 6-2 win over Benesova of the Czech Republic. Joining her is No. 8 seed Francesca Schiavone of Italy, who defeated Russia's Ekaterina Makarova 6-1, 6-3 in a game that was temporarily due to rain. Recent Wimbledon champion and No. 7 seed Petra Kvitova of the Czech Republic is also through after battling Spain's Anabel Medina Garrigues to a 7-6 (3), 6-3 win.

Earlier the day, a match between the top two Chinese players in women's tennis never materialized. Shuai Peng pulled out of her second-round match against world No. 6 Li Na with a left hip injury.

In Wednesday's other morning match, Lucie Safarova of the Czech Republic ousted Romania's Simona Halep 6-2, 6-4.