Naomi Osaka will contest her first WTA Tour quarter-final of the year after producing a classy display to defeat Elise Mertens 6-3 6-3 in the last 16 of the Bad Homburg Open.

Having played her first-round matchup – a 6-4 6-1 win over Magdalena Frech – across two days due to a rain delay, Osaka was determined to ensure swift progression on Tuesday.

She only needed 67 minutes to eliminate the world number 21, setting up a potential last-eight showdown with French Open champion and second seed Mirra Andreeva.

Osaka started as she meant to go on by winning the first five games, and although a small wobble saw Mertens claw the opening set back to 5-3, the four-time grand slam champion recovered her composure to serve it out.

And nothing truly changed in the second set as Osaka continued to dictate proceedings, getting a break in game three then threatening another in game seven, as Mertens was forced to save four break points. 

Having only given up four points on serve throughout the second set, Osaka got the job done by impressively breaking again to love.

She will be joined in the last eight by Emma Navarro, who defeated Eva Lys in straight sets earlier on Tuesday, and Xin Wang, who got past Leylah Fernandez. 

Elena-Gabriela Ruse also advanced by upsetting Berlin Open champion Linda Noskova 6-1 6-3, while Ekaterina Alexandrova edged out Ann Li 6-1 6-7 (5-7) 6-1.

Osaka continues impressive Wimbledon warm-up

Having been forced to withdraw from last week's Berlin Open, Osaka has not skipped a beat at her first grass-court event of the year.

She struck 22 winners compared to just seven unforced errors in a commanding victory, while she only gave up one break point and created nine for herself – converting four.

Osaka has now won six of her last seven matches against top-50 opponents since the start of Roland-Garros, where she reached the fourth round before going down to Aryna Sabalenka.

A potential first career meeting with Andreeva, who faces Ekaterina Alexandrova in her opener on Wednesday, would represent another big test for Osaka as she builds towards the year's third slam.

Osaka last reached a quarter-final at a Tour-level event last October, on home soil at the Japan Open, only for a leg injury to force her to withdraw.