Four-time Grand Slam champion Maria Sharapova made light work of the Czech Republic's Klara Koukalova to ease into the second round of the Madrid Open 6-1, 6-2 on Sunday.

Sharapova claimed her first title of the year in Stuttgart two weeks ago and continued her return to form after a difficult start to the year to seal victory in little over an hour.

Last year's finalist in Madrid will next face unseeded American Christina McHale in the second round.

It was a more difficult afternoon for fifth seed Petra Kvitova as she need a final set tie-break to overcome Romanian Sorana Cirstea 6-1, 5-7, 7-6(7/4).

The former Wimbledon champion looked well on course for the second round after racing through the opening set, but was then broken four times in the second as the world number 27 levelled the match.

Elsewhere, 11th seed Ana Ivanovic overcame Madison Keys in straight sets 6-1, 7-6 (7/4).