PARIS, France - Ana Ivanovic kicked off her French Open title defense with a close straight set win over Sara Errani, but not everything went to form on Day 1 of the year's second Grand Slam tournament.

Ivanovic, who won her first major here last year and subsequently rose to No.1 in the world, has struggled to maintain the world-beating form, winning just one title since - indoors at Linz last fall. Ranked and seeded No.8 now, the Serb spent over two hours on court but still got the win, beating gritty Italian Errani in a tight one, 76(3) 63.

"I was very happy to be back on the center court. I was surprised how many people were there supporting us. It was great to see. I just enjoy competing out there," Ivanovic said. "I knew I had to work hard for my points today. I kept my composure even when I was making some mistakes. I had to work my way into the match and I'll have to work my way through the tournament."

Other seeds winning their first round matches on Sunday were No.9 seed Victoria Azarenka, No.11 seed Nadia Petrova, No.25 seed Li Na, No.27 seed Anastasia Pavlyuchenkova and No.32 seed Iveta Benesova.

The first two upsets of the fortnight saw No.16 seed Amélie Mauresmo lose to Anna-Lena Groenefeld, 64 63, and No.19 seed Kaia Kanepi lose to qualifier Yaroslava Shvedova, 76(2) 36 62. Both results weren't only surprising on paper: Mauresmo has had some stellar results this year, winning her 25th Sony Ericsson WTA Tour singles title at Paris [Indoors] and reaching the semis of Madrid two weeks ago, while Kanepi made it to the quarterfinals here last year.

Other winners were Gisela Dulko, Elena Vesnina, Julie Coin, Kristina Barrois, Timea Bacsinszky and qualifiers Arantxa Rus and Vitalia Diatchenko.