Emma Raducanu booked her place in the quarter-finals at Queen's with a 6-4 6-1 victory over Slovakian Rebecca Sramkova.

The 22-year-old will officially become British number one on Monday after Katie Boulter bowed out with a 2-6 6-3 6-2 second-round defeat to Russian fifth seed Diana Shnaider.

And while she has played down her expectations ahead of this week - pointing to her ongoing back issues - Raducanu looked to be cruising after claiming her first break in the opening game before winning the following four.

But Sramkova was determined to stay in it, saving two set points before breaking the Briton's serve in the sixth, eventually reducing the deficit to 5-4 before Raducanu regrouped, holding to love to seal the first set.

It was a similar story in the second as Raducanu swiftly sealed a double break then made it 4-0.

The Slovakian, four places lower on the WTA rankings than number 37 Raducanu, dug deep again, saving three break points in the fifth game to win her first of the set before the home favourite ensured she was a game away with a backhand to hold the sixth.

And while she could not close out the match at the first time of asking, Raducanu would not be denied again as she punched her ticket to the last eight with another break.

"I'm really pleased to get through that," Raducanu said on court. "It wasn't easy, I don't think it was my cleanest performance, but I'm really happy to have pushed through in some tight moments that decided the first set.

"It was really helpful when it was coming back in the first set to have that roar of support to help me get through that last service game, so I appreciate that!"

Boulter, who replaced 2021 US Open winner Raducanu in top spot exactly two years ago, looked sharp in her first set, saving two break points, breaking the Russian's serve twice, and hitting 10 winners.

But, after landing close to three quarters of her first serves in the first set, the issues that had plagued Boulter in her gritty victory over Australian qualifier Ajla Tomljanovic on Monday returned to haunt her in the second and third sets on an afternoon the Briton double-faulted nine times.

"I actually think today, the first set was some of the best grass court tennis I have played," said Boulter, who now turns her attention to defending her title at Nottingham next week.

The timing of this new tournament - the first time Queen's has hosted women's tennis in 52 years - means Boulter is down points, because she won Nottingham last year in the same week, allowing Raducanu to just usurp her for the time being.

Boulter added: "I'm very happy for her to be British number one, but at the same time, it's going to be fun for me to chase her now, and I think she's been doing that for a while. Now it's kind of my turn."

Briton Heather Watson also bowed out in the last 16 after she was beaten 6-4 6-2 by former Wimbledon champion and fourth seed Elena Rybakina.