The women's tournament lost one of its big favourites in unfortunate circumstances as fourth seed Kiki Bertens retired through illness in the early stages of her second-round match against Viktoria Kuzmova.

Bertens was trailing her Slovakian opponent 3-1 when she stopped playing midway through the next game and called for the doctor. After reporting she was feeling shaky and had no energy, a tearful Bertens shook hands.

The Dutchwoman later revealed she had come down with a stomach bug on Tuesday night.

She said: "Yesterday I felt good. No problems at all. I was practising, resting, and I felt really well. Ready for today.

"And then this morning I woke up at 3am, and then I felt really sick. Vomiting, diarrhoea all night long, all day long. I felt a little bit better before the match. I had some sleep and I just wanted to give it a try but then, as soon as I started warming up right before the match, it started again.

"There was not any energy left. I just wanted to give myself the chance to play and see what's happening. But it was better maybe not to step on the court today."

Bertens has climbed to fourth in the world rankings and beat defending Roland Garros champion Simona Halep in the final of the WTA Tour event in Madrid earlier this month to cement her status as a likely title challenger here.

"It's really bad timing," she said. "It's been a great few weeks, and then if you feel like this during a grand slam where you felt good, it's just really annoying."

Bertens was not the only player to withdraw, with Canadian teenager Bianca Andreescu pulling out ahead of her scheduled second-round match on Thursday because of ongoing shoulder problems.

The 22nd seed caused a real stir by winning the title in Indian Wells in March but has been sidelined virtually ever since.

Second seed Karolina Pliskova has been making swift progress through the draw so far and was detained for only 56 minutes by Kristina Kucova in a 6-2 6-2 victory.

Pliskova, a semi-finalist here two years ago, arrived in Paris with her confidence sky high after winning the big WTA title in Rome earlier this month.

Ukraine's Kateryna Kozlova was another player to withdraw through illness, giving ninth seed Elina Svitolina a free passage through to the third round, where she will take on former champion Garbine Muguruza, who eased to a 6-4 6-1 victory over Johanna Larsson.

Last year's runner-up is also through, seventh seed Sloane Stephens defeating Sara Sorribes Tormo of Spain 6-1 7-6 (3).