British number one Emma Raducanu was knocked out in the last 16 of the Indian Wells Masters to top seed Iga Swiatek, while Jack Draper retired injured against Carlos Alcaraz.
Raducanu went down 3-6 1-6 to world number one Swiatek, while Draper was a set and a break down to Alcaraz before being forced to withdraw with an abdominal issue.
Fighting off injury and illness, Raducanu had enjoyed a wholly positive week in California, beating Danka Kovinic, Magda Linette and Beatriz Haddad Maia to reach the fourth round.
However, the former US Open champion was blown away in just one hour and 24 minutes by Swiatek, who crucially beat away two break points for Raducanu in the third game of the match.
The world number one broke to love in the sixth game en route to a comfortable first-set triumph, and an opening hold in the second set would be the only thing Raducanu had left to cheer for the remainder of the match.
The 20-year-old saved four break points in the third game before succumbing to Swiatek's superiority, as the Pole embarked on a five-game winning streak to ease into the last eight.
"I think that Iga played a very good level and showed why she is number one in the world. She was very ruthless with the way that she played," Raducanu told BBC Sport after the match.
"I think I was able to stay competitive for the beginning of the match but ultimately she ground me down and by the end of it I was just taking way too long to recover from one rally."
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Meanwhile, rising star Draper - who defeated Andy Murray in their first-ever competitive meeting to set up a tie with Alcaraz - saw his own eye-catching run at the Masters 1000 event cruelly cut short by injury.
The 21-year-old was fighting an uphill battle to save his Indian Wells bacon anyway, having fallen 2-6 0-2 down to the reigning US Open champion before a stomach problem forced him to quit.
Alcaraz got off to a dream start with a break in the opening game of the match, but Draper missed a gilt-edged opportunity to break back straight away, letting a 40-0 lead slip through his grasp.
Alcaraz broke once more in the fifth game and posted two love holds to wrap up the first set in just 37 minutes, and Draper was again broken right off the bat in the second set.
Following another love hold for Alcaraz, Draper threw in the towel as his abdominal issue bedevilled him, with the 21-year-old also revealing that he had struggled with hip pain following his win over Murray.
"I was doing further damage, so there was no point in making it worse. At the end of my match against Andy [Murray, on Monday], I obviously had a bit of hip pain but my ab towards the end was getting sorer," Draper added.
"I'm still early in my development. I'm starting to play Grand Slams with five sets. The physical nature of this sport is very demanding and so you've got to have a really resilient body to cope with the demands of the tour."
Draper is reportedly set to undergo a scan on Wednesday to determine the severity of his injury, leaving Cameron Norrie as the only Briton left standing in the singles tournament as he prepares to face Frances Tiafoe in Wednesday's quarter-final.
