Australian qualifier Rinky Hijikata stunned Czech second seed Jiri Lehecka with a 4-6, 7-5, 7-6 (9/7) victory to reach the Queen's Club quarterfinals in on Thursday.
Hijikata is ranked 92 places below Lehecka, but he shrugged off that vast gap with a vibrant display at the Wimbledon warm-up event in west London.
World number 12 Lehecka finished as Queen's runner-up last year and is regarded as an emerging force on the ATP Tour.
Despite losing the first set, Hijikata battled back by taking the second set and clinched his memorable success in a tense final set tie-break.
The 25-year-old is into the quarterfinals of the grass-court tournament for the second time after his run in 2024 when he was also a qualifier.
"It was all pretty difficult. I went down an early break in both the first and second sets," Hijikata said.
"He didn't make life easy. It was a tough match all the way through and then at the end, there was only a point or two difference."
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— ATP Tour (@atptour) June 18, 2026
In the London sunshine, @rinky_23 stages a brilliant comeback to knock out second seed Lehecka and reach the last eight! @QueensTennis | #HSBCChampionships pic.twitter.com/fKhlxE9LL0
The world number 104 will meet France's Ugo Humbert or Serbia's Hamad Medjedovic in the last eight.
Tommy Paul moved into the quarterfinals, beating Botic van de Zandschulp 7-6 (7/5), 6-3 as the American chases his second Queen's title.
Paul, seeded eighth, is undefeated in his last seven matches at Queen's since losing to Francisco Cerundolo in 2023.
The 29-year-old, who won the Queen's crown in 2024 and missed last year's event through injury, is bidding to join an exclusive club of Americans.
John McEnroe, Jimmy Connors, Pete Sampras and Andy Roddick are the only other multiple title winners at Queen's in the Open era.
"The beginning of the match he came out firing. I just told myself to stick around. The level got really high in the first set," said Paul, ranked 28th in the world.
"I was zero and two against him before this match. I definitely knew it was going to be a tough one so it was really nice to get the win today."
Corentin Moutet courted more controversy on the Andy Murray Arena in a 6-4, 6-3 defeat by Alejandro Davidovich Fokina.
The 27-year-old Frenchman had created a stir by swearing repeatedly during a live courtside television interview after his first round win over Giovanni Mpetshi Perricard.
During his loss to Davidovich Fokina, Moutet slipped on the court and then angrily slammed his racket into the surface.
Moutet aimed some colourful language in French towards his coaching team and hit a ball out of the stadium after losing match point.
Spanish fourth seed Davidovich Fokina faces Paul in Friday's quarterfinals.