Shortly after, on Court Suzanne-Lenglen, another title favourite suffered a shock defeat as No.5 seed Kiki Bertens stumbled out 6-4, 6-4 to Italian qualifier and world No.159 Martina Trevisan in 95 minutes.
"I'm living in a dream. I came here two weeks ago to my Roland-Garros qualifying but today I'm here in the quarter-finals," said the 26-year-old lefty, who is the first Italian woman to make the quarter-finals in Paris since Sara Errani in 2015.
"Oh my God, I can't believe it. I'm really honoured to play in this court with Bertens, because she's an incredible player. I can't believe it."
Trevisan, who saved two match points in her win over Maria Sakkari two days earlier, is making her Roland-Garros debut. After 16 straight losses to top-100 players across all level between 2017 and 2020, she has now posted four consecutive wins over such opponents in one week.
Trevisan and Swiatek will square off in the last eight.