Stosur knocked out by No.156 in Nottingham

Britain's Katie Boulter has claimed one of the best victories of her career against former US Open champion Sam Stosur to reach her first WTA Tour quarter-final at the Nottingham Open.

The 21-year-old, ranked No.156, has made significant strides in 2018 and powered to a 7-6 (8-6) 6-1 victory over Stosur, the winner at Flushing Meadows in 2011.

Boulter will next face either top seed Ashleigh Barty or Duan Yingying of China.

"It's really exciting. It's a huge step for me," Boulter said. "She's a grand slam winner, and it's the first one of those that I've beaten. It was a really quick second set but I dug in really deep in the first. I thought I held my nerve really well and found a way to win."

Johanna Konta won an all-British battle against Heather Watson to join Boulter in the last eight.

It was a second meeting on the WTA Tour for Britain's top two female players and, like the previous one in Indian Wells last year, Konta came out on top.

The windy conditions made life difficult for both players but ultimately it was the extra power of Konta, who reached the final here 12 months ago, that made the difference in a 6-4 7-6 (7-5) victory.