A candid Nick Kyrgios said rising to the big occasion was never likely to be a problem after his quarter-final victory over Rafael Nadal at the ATP Western & Southern Open, but conceded he has been guilty of tanking against lesser opponents.
It was Nadal's second match of the day, defeating countryman Albert Ramos-Viñolas earlier in the day.
Nadal will return to world No.1 next week after nine years away from the top spot, the longest gap in ATP rankings history.
Both Nadal and Kyrgios had to play two matches on Friday because their scheduled contests on Thursday were postponed by rain.
Back-to-back matches for top seed and incoming world number one Nadal appeared to catch up with him as he lost in straight sets to Kyrgios on Friday.
Elsewhere, seventh-seeded Bulgarian Grigor Dimitrov sailed past Japan's Yuichi Sugita 6-2, 6-1. He saved the first break opportunity for Nadal and had match point once again, but an errant forehand on the second break point gave the one seed, the break back. 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.
Kyrgrios earlier beat Croatia's Ivo Karlovic 4-6 7-6 (8-6) 6-3.More news: Knife Attacker In Russian City Injures Eight
More news: Environmental Streamlining EO Opens Critical Relief Valve to Build Additional Infrastructure
More news: Something weird is happening with Taylor Swift's social media
Kyrgios looked the fresher of the two players as he dismantled Nadal in the opening set and kept his composure in the second.
There was one last nice moment left for Kyrgios, as instead of the now traditional autograph on the court-side camera, he wrote "Barcelona" with a loveheart, in solidarity with the victims of Thursday's Las Ramblas attack. "So I just need to be ready to play my best".
"He obviously is a tough match always", said Nadal. He had some mistakes and I was able to be back in the match.
But Nadal was below his best against the maligned Australian and four-time ATP Tour victor, who will face David Ferrer in the final four, having never progressed beyond the second round in Cincinnati previously.
Romania's Halep plays Britain's Johanna Konta, who has won each of their three previous meetings, in their quarter-final tie later on Friday (not before 00:00 BST on Saturday).
Isner - the 2013 runner-up - awaits in the semis after he saw off fellow American Jared Donaldson 7-6 (7-4) 7-5.