's-Hertogenbosch (Netherlands), June 11 (IANS): Former World No.1 Naomi Osaka kicked off her grass-court season with a win at the Libema Open, defeating No.32 Elise Mertens in straight sets in the first round on Tuesday. Osaka defeated Mertens 6-2, 6-4 to register her first win on grass since the 2019 Wimbledon.

Making her tournament debut in Rosmalen, Osaka made good of the wild card into the main draw of the event.

Following up on her outstanding performance in the second round of the French Open, where she held match point on eventual champion Iga Swiatek, Osaka's sublime serving and crisp baseline hitting was once again on full display in the 70-minute victory.

Osaka improved her head-to-head over Mertens to 4-2 with an unbreakable serving performance. After saving break point in her second service game, Osaka did not face a break point for the remainder of the match, winning 90 percent of her first-serve points.

She was also perfect on her own break-point chances, breaking Mertens three times.

Pegula victorious in injury comeback

Meanwhile, world No.5 Jessica Pegula eased past Aliaksandra Sasnovich in another first-round match here, winning 6-2, 6-2 on Tuesday.

The victory is Pegula's first since leading the United States to victory at the Billie Jean King Cup in April. After a two-month injury break, the American is playing her first Hologic WTA Tour tournament since the Credit One Charleston Open in April.

Pegula is the top seed in both doubles and singles this week in 's-Hertogenbosch. Facing No.70 Sasnovich, Pegula showed no signs of rust from her competitive break.

She played a clean and disciplined match off the ground, hitting nine winners to just six unforced errors to seal victory in 58 minutes. She broke Sasnovich five times from seven break points and was broken just once herself.