MONTRÉAL, Canada - Ana Ivanovic made a winning start to the summer hardcourt season on Wednesday, powering past Petra Kvitova in straight sets at the $1.34-million Rogers Cup presented by National Bank. It was a good day for most of the seeds in action with the exception of Maria Kirilenko and Flavia Pennetta, who were both beaten in three sets.

Ivanovic, who has been the world's No.1 player since winning her first Grand Slam title at the French Open and is the top seed here, looked a bit shaky in the second and third sets but managed to close out the hard-hitting Czech, 63 46 63, although at one point she led 5-0 in the third.

"It wasn't the best match I've played," Ivanovic said. "She played a match before this week and for me it was the first match since Wimbledon. So in the beginning I obviously struggled to find my rhythm a little bit. But I'm happy I won. You have to win even if you don't play your best. That was the case for me today."

Montréal has been a memorable venue for Ivanovic, who won her first Tier I title in her only previous appearance in this city two years ago. The Rogers Cup in general hasn't been as peachy for her, however; in her two attempts in Toronto she has had early exits, including losing her opening match last year.

Other seeds advancing in the day session were No.6 seed Anna Chakvetadze, a 62 75 winner over Jill Craybas; No.7 seed Dinara Safina, who improved to 23-3 since the European clay court season with a 62 64 win over Anastasia Rodionova; No.9 seed Patty Schnyder, a 61 75 winner over Monica Niculescu; No.11 seed Victoria Azarenka, a 62 62 winner over Sybille Bammer; and No.12 seed Nadia Petrova, who beat Tamarine Tanasugarn, 63 62. No.10 seed Marion Bartoli moved into the third round when her opponent, Alisa Kleybanova, withdrew prior to their match due to a low back injury.

Two seeds, Maria Kirilenko and Flavia Pennetta, weren't so lucky. Pennetta, the No.15 seed and a finalist at Los Angeles last week, was ousted by 15-year-old phenom Michelle Larcher de Brito, 63 06 63; No.13 seed Kirilenko followed her to the sidelines with a 62 26 76(4) loss to Canadian wildcard Stéphanie Dubois. Larcher de Brito picked up her second career Top 20 victory, having beaten Agnieszka Radwanska earlier this year; Dubois got her first Top 20 victory.

"At the end I was still believing I could do it; I managed well on the important points," said Dubois, who showed some strong nerves to come back as Kirilenko served for the match at 5-4 in the third set. "I'm really happy right now I pulled it through. I didn't want to lose this match. Obviously, Maria played a good match. She's a top player. She has won two titles this year. Every point was tough."

Winners in matches between unseeded players were Ai Sugiyama, a 62 62 winner over Shahar Peer, and Tamira Paszek, a 64 75 winner over Melinda Czink.

The last two second round matches took place under the lights. No.3 seed Maria Sharapova kicked off the evening proceedings with a 75 57 62 win over Marta Domachowska in a match that lasted five minutes short of three hours. She struggled with her right shoulder throughout the lengthy match, and afterwards announced she was withdrawing from the tournament because of it.

"Coming into this tournament I wasn't sure if I was going to be able to compete," Sharapova said. "In the last few weeks I've been trying to find a solution to the aggravation I did to the shoulder back at Indian Wells in one of my matches. I haven't found the solution yet. I just spoke to a couple of doctors and they advised me to try to find the cause of the problem, what's causing my bursitis, because they think there's something else behind it rather than just that."

No.2 seed Jelena Jankovic and Aleksandra Wozniak were the last players to take the court and Jankovic dashed the Canadian's upset hopes with a 60 64 win.

"The first match is always tough; playing against a Canadian, knowing that the crowd will be against me, knowing all the circumstances, it's not so easy," Jankovic said. "But I was able to stay focused and was able to get through the match. I'm happy with that and looking forward to my next match."

"Obviously she played a great match today," Wozniak said. "She didn't make any mistakes. She played so cleanly in the first set and it went by so fast. In the second set I did better, stepping into the short balls and being more aggressive; but I think I made some errors and didn't take my opportunities. I'll just have to go forward from here and look to the future."

Ivanovic wasn't the only No.1 seed to win an opening match on Wednesday. Cara Black and Liezel Huber, seeded No.1 in the doubles draw, won their first match of the week against Liga Dekmeijerre and Angela Haynes, 75 62.