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.

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