Katie Boulter suffered a last-16 exit at Queen’s to fifth seed Diana Shnaider and will now relinquish her title as British number one for the first time in two years.
The 28-year-old battled hard but lost 2-6 6-3 6-2 on a hot but rain-affected day in west London.
Boulter has held the top spot in British tennis since June 2023 but Emma Raducanu will now move ahead of her in the rankings.
With Boulter out, it is over to two more Britons to try for a place in the quarter-finals at the first women’s Queen’s event since 1973.
Heather Watson takes on 2022 Wimbledon champion Elena Rybakina before Raducanu faces Slovakia’s Rebecca Sramkova later on Thursday.
Boulter, bidding to reach a seventh quarter-final on grass, had expressed concern about her serve earlier in the week, suggesting she would be working on it in the build-up to this match.
But no such troubles were apparent in the opening set against Shnaider as Boulter continually caused problems behind her first serve.
Having saved a break point then secured an impressive break to love with a crowd-pleasing volley, Boulter battled to consolidate with an important hold, saving another break point along the way.
She then took the double break with a sweeping forehand and more solid serving handed Boulter the opening set as rain threatened to come down in west London.
But by the time the umpire suspended play because of a downpour, Boulter was down a break at 4-1 and in trouble on serve again.
After a 20-minute rain delay, she returned to be broken for a second time and, despite recovering one break, she could not prevent Shnaider from taking the second set and forcing a decider.
Boulter once again found herself under the cosh in the opening game, wiping out three break points to secure the hold as problems on serve returned with a vengeance.
She saved more break points in her next service game only to double fault and concede the break.
From there, Boulter struggled to regroup and went a double break down. She could not find a way back in her bid to book a fifth quarter-final in a WTA 500 event as Shnaider set up a meeting with American second seed and Australian Open champion Madison Keys.
