Australia's Nick Kyrgios humbled new world number one Rafael Nadal 6-2, 7-5, winning twice in one day to reach the WTA and ATP Cincinnati Masters semi- finals.

On a day when defending champion Karolina Pliskova won twice in one day for the third time this season to tighten her grip on the world number one ranking, Kyrgios stole the show by overpowering the 15-time Grand Slam champion after each had won earlier. The 22-year-old from Canberra was up a double break in 10 minutes, seizing the chance to make a between-the-legs showoff shot on his way to a 4-0 lead, drawing boos from the crowd.

Kyrgios, ranked 23rd, took the first set in 25 minutes, dropping only three points on his serve while taking seven- of-eight points off the 31-year-old Spaniard's second serves.

Nadal netted a forehand to surrender a break and a 3-2 lead to Kyrgios in the second set. The Aussie served for the match in the 10th game but double faulted on his third match point and Nadal had new life, screaming, "Come On." But Kyrgios broke again to lead 6-5 and this time end matters with his 10th ace after 80 minutes, improving to 2-2 all-time against Nadal and booking a Saturday semi-final against Spain's David Ferrer.

Earlier, Kyrgios defeated Croatia's Ivo Karlovic 4-6, 7-6 (8/6), 6-3 and Nadal downed compatriot Albert Ramos-Vinolas 7 -6 (7/1), 6-2. Kyrgios, who matched his best ATP Masters runs from Miami the past two years, seeks his fourth career title after 2016 trophies at Marseille, Atlanta and Tokyo.

Pliskova, fighting to hold off Romania's Simona Halep atop the rankings, first ousted Italian qualifier Camila Giorgi 6-3, 4-6, 6-0 in one of five matches postponed from Thursday due to rain. With only two hours between matches, the 25-year-old Czech defeated Denmark's fifth-ranked Caroline Wozniacki 6-2, 6-4 to book a Saturday semi-final against Wimbledon champion Garbine Muguruza.