Australia's Nick Kyrgios humbled new world No 1 Rafael Nadal 6-2, 7-5 on late Friday, 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 No 1 ranking, Kyrgios stole the show by overpowering the 15-time grand slam champion after each had won earlier.
The 22-year-old player 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 Australian 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.
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Bulgaria's 11th-ranked Grigor Dimitrov plays American John Isner in the other semi-final.
Nadal took only 6-of-20 second serve points and won only five off the Aussie's first serve.
Earlier, Kyrgios defeated Croatia's Ivo Karlovic 4-6, 7-6, 6-3 and Nadal downed compatriot Albert Ramos-Vinolas 7-6, 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.
And he served notice for the US Open, where he has never reached the fourth round. The year's last grand slam event starts August 28.
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.
"I feel pretty good," Pliskova said. "I recover well, so definitely I will be ready for tomorrow."
Second-ranked Halep eliminated British seventh seed Johanna Konta 6-4, 7-6 to book a semi-final date with US wildcard Sloane Stephens.
"Whatever comes I will just take it," Pliskova said. "Even if I would be second coming to the US Open, it's still better than I was last year. So no pressure about being world No 1."
Pliskova's two-in-one effort, matching feats on her way to Eastbourne and Doha titles, means Halep must capture the crown to swipe the top spot in Monday's rankings.
"Not always is it going this way," Pliskova said of her twin wins. "It's just lucky that I always won both of them."
Nadal, who won his 10th French Open title in June, was assured of moving into the top ranking on Monday for the first time since July 2014 when Roger Federer withdrew from Cincinnati with a back injury.
Nadal and Ramos-Vinolas wore black ribbons on their shirts in memory of victims of the terror attack Thursday in Barcelona.
"What happened yesterday in Barcelona was, of course, terrible. Everyone is very, very sad. I don't have words to say, because when these kind of things happen, is difficult," Nadal said.
"All my support to Barcelona and especially to the people that are suffering a lot, for all the families of the victims. Just keep going and sorry for everything."
Drawing on a camera lens after the final match, Kyrgios wrote "Barcelona" and drew a heart.
Sixth-ranked Spaniard Muguruza, wearing a black ribbon on her visor, ousted Russian eighth seed Svetlana Kuznetsova 6-2, 5-7, 7-5 in a matchup of two-time Grand Slam winners.
Ferrer upset Austria's eighth-ranked Dominic Thiem 6-3, 6-3 while Isner fired 25 aces in beating American wildcard Jared Donaldson 7-6, 7-5 and Dimitrov downed Japan's Yuichi Sugita 6-2, 6-1.