British number one Johanna Konta began her Madrid Open campaign with a 6-4 6-1 win over American Alison Riske.

Only a day after losing the Morocco Open final to Maria Sakkari in three sets in Rabat, the world number 47 faced Riske, ranked two places lower.

From 4-1, she was pulled back to 4-4 but took the next five games and sealed the match in an hour and 14 minutes.

In round two, the 27-year-old faces world number three Simona Halep, who beat Margarita Gasparyan 6-0 6-4.

Konta, seeking her fourth WTA title, had won her only previous meeting with 28-year-old Riske and a superb angled forehand return gave her set point, which she duly secured with a backhand of precision into the corner.

A Riske double-fault gave Konta a 2-0 lead at the start of the second set and the Briton sealed victory with an ace at just after 9pm local time.

Unseeded Pauline Parmentier of France eliminated sixth seed Elina Svitolina, who had been struggling with a knee injury, 6-4, 7-6 (8-6), while 13th seed Madison Keys lost 3-6 6-4 6-1 to Sorana Cirstea of Romania.

Former world number one and fourth seed Karolina Pliskova saved five match points to deny Ukrainian teenager Dayana Yastremska 5-7 7-6 (7-5) 6-3.

The 11th seed Caroline Wozniacki was trailing 3-0 when she retired with a lower back injury from her first-round match against world number 54 Alize Cornet of France.