Holder Ana Ivanovic was made to sweat much more than expected in a 7-6 6-3 victory over unheralded Italian Sara Errani to reach the second round of the French Open yesterday.

The eighth-seeded Serb needed two hours and two minutes to break the resilience of Errani to set up a meeting with either Camille Pin or Tamarine Tamasugarn.

"I expected a tough match. I knew I would have to work hard for my points today, and I'm very happy I did that," Ivanovic told reporters.

"I kept my composure even when I was making a few mistakes."

Ivanovic, who had only won two matches on clay this season before arriving at Roland Garros, threw away 10 break points in the first set and was stretched into a tiebreak which she claimed after 72 minutes.

Errani lost focus in the tiebreak after contesting a call and she paid for it by allowing Ivanovic to move 5-2 up and clinch it 7-3.

Ivanovic staved off four break points in her opening service game of the second set before moving 5-1 up and although Errani pulled a break back, the 21-year-old Serb wrapped up the win on her third match point with a smash.

Meanwhile, Leyton Hewitt felled lofty Croatian Ivo Karlovic 6-7 6-7 7-6 6-4 6-3 to reach the second round. Standing at 2.08 metres, Karlovic is the tallest man in tennis and looked poised to hand the Australian his earliest Roland Garros defeat in a decade.

But Hewitt, never one to give up without a fight, hung on for almost four hours to seal his passage into the last 64 when Karlovic misfired a smash well beyond the baseline.