Kyrgios knocked out the new No. 1 in the quarters, 6-2, 7-5.
Nick Kyrgios scored an upset victory in the quarterfinal of the Cincinnati Masters to beat No. 1 Rafa Nadal, 6-2, 7-5.
Nadal reached the No. 1 spot this week after Federer pulled out of Cincinnati after tweaking his back in Montreal the week before. It's Nadal's second straight disappointing performance in the lead-up to the US Open—he lost to 18-year-old Denis Shapovalov in the quarters in Montreal—and marks his third consecutive tournament exited before the semifinal (he lost to Gilles Muller in the round of 16 at Wimbledon).
The volatile Kyrgios, ranked 23rd in the world, served for the match at 5-4 in the second set but double faulted multiple times to hand Nadal the break. Despite a crowd that was vocal in its support for the Spaniard, Kyrgios responded to the disappointing break by breaking Nadal in the very next game. Kyrgios managed to hold to score the upset victory and put an exclamation point on the match by acing Nadal on match point.
Kyrgios will face David Ferrer in the semi after Ferrer beat Dominic Thiem 6-3, 6-3 in a quarterfinal match.