The world No.1 returns to the semi-finals with world No.20 Daria Kasatkina standing in her path.
Thursday will witness Swiatek's third career Grand Slam semi-final appearance and her second of the year.
Story of the match
Once again Swiatek made a fast start, skipping to the backhand corner to unleash an inside-out forehand winner for an immediate break.
With the Pole racing 40-0 up, it looked like world No.11 Pegula was in for a torrid time on Court Philippe-Chatrier, but the American dug in and claimed five successive points to rebound for 1-all. An eight-minute hold later and Pegula was on the front foot.
Not quite. Swiatek capped a riveting rally with a cross-court backhand winner, moments before sprinkling in some true magic.
The 21-year-old chased what seemed to be a lost cause from a deft Pegula drop shot and mid-slide, nearly in the split position, directed the ball towards the umpire’s chair for a decisive 4-3 break.