BIRMINGHAM: World number one Naomi Osaka succumbed to a straight-sets defeat by Yulia Putintseva at the Birmingham Classic on Thursday, handing Ashleigh Barty the chance to end the week on top of the rankings.

Osaka admitted ahead of her first grass-court tournament of the season that she is still not at home on the surface and it showed as Putintseva romped to a 6-2, 6-3 win.

The US and Australian Open champion now runs the risk of heading into Wimbledon short of match practice on the grass as she has not signed up to play in Eastbourne next week.

Putintseva made a blistering start to go 5-0 up in the first set and Osaka's troubles on serve throughout the match ensured she never recovered.

Osaka dropped serve at the start of the second set, but fought back to lead 3-2 before Putintseva won the last four games to close out the match in a little over an hour.

"I needed to be more free with my shots, and not worry about what happens. I was more aggressive and changed the rhythm; that helped me win the match," said Putintseva.

French Open champion Barty can secure the world-number-one spot by winning the title in Birmingham and she eased into the quarter-finals with a 6-3 6-1 victory over Jennifer Brady.

"The stars have aligned a little bit for me and I think when you get those opportunities you have to do your best to take them with both hands," said Barty.

"That's what we have been able to do over the last month in particular but I feel like I'm comfortable in my own skin.

"I feel like I know exactly how I want to play in most matches, and it's just about going out there trying to execute as best I can."

Only the rain threatened to slow Barty as it delayed the start of the match and then briefly interrupted the second set.

However, Barty was too focused and too good for Brady and made it nine wins in a row after claiming her maiden Grand Slam title in Paris earlier this month.

Barty will face five-time Wimbledon champion Venus Williams in the last eight on Friday after the 39-year-old was too wily for Wang Qiang in a 6-3, 6-2 win.

Julia Goerges is next up for Putintseva after the 2018 Wimbledon semi-finalist defeated Russia's Evgeniya Rodina 6-4, 6-3. —AFP