Madison Keys notched her first win over a reigning world No. 1. (Robert Prange/Getty Images)

Madison Keys stunned No. 1 Iga Swiatek at the Western & Southern Open on Thursday to advance to the tournament’s quarterfinals.

The 27-year-old American charged to a 6-3, 6-4 victory over Swiatek, marking Keys’ first win over a reigning world No. 1. Swiatek got the better of the duo’s two previous meetings leading up to Cincinnati.

“I obviously have not had the best success against World No. 1s, so being able to get a win against Iga, especially after having two losses to her already, means a lot to me, and I think I’m playing some pretty good tennis,” Keys said following the match.

Keys’ big hitting helped her clinch the breakthrough win over Swiatek, as she blasted 14 winners to the world No. 1’s six.

Swiatek has now incurred three straight third-round losses, holding a 4-4 record since her historic 37-match winning streak ended at Wimbledon.

Keys will meet world No. 25 Elena Rybakina in the Western & Southern Open’s quarterfinal round, with the Wimbledon champion yet to lose a set so far in the tournament.