Updated

By Mark Meadows

PARIS (Reuters) - Inconsistent champion Francesca Schiavone ambled into the French Open fourth round Friday after China's Peng Shuai became the second player in the women's draw to suffer debilitating health problems.

The Italian was leading 6-3 1-2 when Peng decided to pull out having been twice checked over by a doctor on court.

Peng said she had been feeling sick with a cough since Tuesday.

"It was very tough to breathe," she told reporters in a hoarse and very quiet voice.

"At the start I was OK, I took some medicine. I just need rest."

Germany's Sabine Lisicki had to be carried off court on a stretcher in floods of tears Wednesday having been on the brink of beating third seed Vera Zvonareva before folding.

She later blamed an intolerance to gluten.

Schiavone, whose grunts got louder with every point, slipped 3-1 down in the first set but used her power rather than finesse to surge back and take a grip of the contest below cloudy skies.

The fifth seed plays former world number one Jelena Jankovic in the next round.

"From now on I've got to up my game of course," she told reporters before cautioning against thinking about the latter stages with second seed Kim Clijsters and last year's runner-up Samantha Stosur already out.

(Editing by Pritha Sarkar)