Petra Kvitova and four former No.1s reached the round of 16 at the Olympic Tennis Event.
WTA Staff

LONDON, England - The second round of the Olympic Tennis Event kicked off Monday, with eight players moving through - including four former No.1s.

Serena Williams, the No.4 seed, was among the winners, needing an hour and 13 minutes to beat the WTA's newest Top 50 star, Urszula Radwanska, 62 63.

"It was tough conditions today, a little windy, but I'm glad I was able to pull through," Williams said afterwards. "I think I played okay. I was excited to be out there, to play solid. I don't think I played badly. Obviously I have to believe I can play better, but for the early rounds, I think I'm playing pretty well."

Next up is No.13 seed Vera Zvonareva, who beat Francesca Schiavone, 63 63. She has always dominated the Italian, now 11-0 in their head-to-head.

"We've always had tough matches against each other but I've managed to win a lot of those," Zvonareva said. "Today was the first time we played on grass, so it was different this time, but no matter what I tried today, it worked. Playing against someone with so much experience like Francesca, it's nice to win."

The tables will be turned in the Russian's next match, though, as Williams is 6-2 lifetime against Zvonareva - Zvonareva did win their last meeting, though.

"It's a good match-up for us both," Williams said. "A Wimbledon final rematch. She's playing so well and doing everything great, so it's not going to be easy. It's going to be tough for me to play against someone so tough so soon."

There is one thing Zvonareva holds over Williams - an Olympic medal in singles, capturing the bronze in Beijing four years ago. "Beijing was a great experience for me. I have so many great memories from there. But it's four years later now and I have to start from zero. That medal will always stay with me, but I have to stay in the moment. The past is the past - you have to keep working hard."

The other No.1s winning were No.11 seed Ana Ivanovic, who edged Elena Baltacha, 64 76(5); Kim Clijsters, who beat Carla Suárez Navarro, 63 63; and No.8 seed Caroline Wozniacki, who beat Yanina Wickmayer, 64 36 63.

"Yanina went out there and played some very good tennis. I really had to dig deep to win that one," Wozniacki said. "I'm really pleased how I managed to come back in the third set and get a lead at the start and win that long game, which I think was 13 deuces. I think that really made the difference today."

She may not be a former No.1 but No.6-seeded Petra Kvitova - who has been as high as No.2 in the world - was also among the winners, recovering after a messy second set and cruising past Peng Shuai in the third, 75 26 61.

"I played so, so bad in the second set. I did a lot of mistakes on my forehand," Kvitova said. "It was a big key to break her in the first game of the third. It wasn't easy - I had a lot of break points - but after that it was much easier."

Flavia Pennetta and Daniela Hantuchova rounded out the winners.