Stuttgart Open: World number one Simona Halep and Angelique Kerber through

Image source, Getty Images

Image caption, Halep won the Shenzhen Open in China earlier this year

World number one Simona Halep came from a set down to beat Slovakia's Magdalena Rybarikova and reach the second round of the Stuttgart Open.

Romania's Halep, who won the Shenzhen Open in China earlier this year, triumphed 4-6 6-2 6-3.

Meanwhile, two-time Wimbledon champion Petra Kvitova was beaten 6-3 6-2 by Germany's Angelique Kerber.

World number 12 Kerber had lost to Czech Kvitova on the same court in the Fed Cup at the weekend.

"I had goosebumps when I came out on court," said Kerber. "It was not an easy match after Sunday.

"My team and I analysed it and we learned from that loss. I am unbelievably happy to be in the second round."

Earlier, seventh seed Sloane Stephens was thrashed 6-1 6-0 by fellow American Coco Vandeweghe, while Anastasia Pavlyuchenkova beat Madison Keys 7-6 (9-7) 5-7 6-4.