Halep beat Swiatek 6-1 6-0 at the same stage of the Paris major last year, but the world number 54 from Poland gained sweet revenge with a magnificent 6-1 6-2 victory on Court Philippe-Chatrier.
Two-time grand slam champion Halep had won a career-best 17 consecutive matches, but she was bulled by the inspired 19-year-old, who hit 30 winners and did not face a break point in a stunning performance.
Swiatek’s reward for a relentless display will be a last-eight showdown with outsider Martina Trevisan or Kiki Bertens in Paris, where the seeds continue to crash out in a women’s draw that is wide open.
The aggressive Swiatek made a blistering start, winning the first three games as she pummelled Halep with thunderous groundstrokes – her forehand in particular firing on all cylinders.
Halep had no answer to the relentless Warsaw native, who went 5-1 up with an exquisite drop shot and wrapped up the opening set in just 24 minutes.
Swiatek showed no let-up at the start of the second set, breaking in the first game and unleashing more rasping forehands in a lengthy fifth game before Halep netted at full stretch to go 4-1 down after saving five break points.
Halep was shellshocked and Swiatek completed an astonishing demolition of the 2018 champion, serving out a one-sided match with nerves of steel.
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