Wimbledon champion Marketa Vondrousova began her grass-court campaign with a straight-set win over Spain's Rebeka Masarova at the Berlin Open.

The 24-year-old won 6-4 6-3 in the German capital and will play Russian Anna Kalinskaya next.

The Czech world number six became the first unseeded player to win the Wimbledon women's singles title with victory over Ons Jabeur in last year's final.

Vondrousova has now won her past eight matches on grass following her maiden Slam triumph at the All England Club last summer.

She had to overcome three break points during the opening set before striking in the ninth game for a 5-4 lead and serving it out.

Vondrousova maintained that momentum and immediately broke Masarova in the second set before establishing a 4-1 advantage with another break of serve.

Masarova responded to reduce the deficit, but Vondrousova closed out victory on the Spaniard's serve to ensure a winning start as she prepares to defend her Wimbledon crown.

Eight of the world's top 10 are competing in Berlin, with only top-ranked Iga Swiatek and world number seven Jasmine Paolini absent.

On Wednesday, Chinese sixth seed Zheng Qinwen begins against four-time major winner Naomi Osaka, Greek seventh seed Maria Sakkari plays two-time Slam champion Victoria Azarenka and Tunisian eighth seed Jabeur meets Wang Xinyu.