The Nick Kyrgios-Rafael Nadal Mexican Open clash was expected to be the mother of all matches between two of the game's great entertainers - and it didn't disappoint.
In a contest of ebbs and flows, Kyrgios outlasted the Spanish champion in just over three hours, winning 3-6 7-6(2) 7-6(6).
It was the sixth meeting between the pair, and the first since Nadal's straight sets victory in the China Open final in October 2017.
So much has happened since that day - Nadal won his 11th Roland-Garros crown and spent time atop the ATP rankings, while Kyrgios copped injury after injury to slump to No. 72 by Thursday's (AEST) match.
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Nadal swept through the first set 6-3 in Acapulco, winning 83 per cent of points on his serve as Kyrgios sent down three double faults.
Prior to the second set, an ailing Kyrgios - with both knees strapped - was overheard contemplating retiring, but staved off the inevitable mainstream media pile-on to scrape himself off his chair.
“I feel sick... if I forfeit, the media will blow it up…. I’ll be booed off the court," he said.
"I’m gonna try to play a couple of more games."
That he did, Kyrgios finding momentum in the second, cracking 10 aces before jogging through the tiebreak to take it to a decider.
The final set was a topsy-turvy affair - neither player could find the decisive break as it crawled to a tiebreak.
Nadal had his chances in the seventh game, but failed to convert several break points as Kyrgios stayed in the match.
Kyrgios led Nadal 4-0 in tiebreaks heading into the final set - he won both in their Wimbledon clash, one in Rome, and the second set on Thursday.
It again remained on serve in the tiebreak until Nadal snatched a mini break to take it to 4-3, then won both of his serves to set up three match points.
However, Kyrgios somehow saved all three to recover to 6-all, and the atmospheric Acapulco crowd - having stresed their way through a thriller - nearly melted as Nadal double-faulted.
Then armed with a match point of his own, Kyrgios did the business as Nadal sent it long, the 23-year-old claiming his first win over the 17-time Grand Slam champion since their Cincinnati quarter-final in August 2017.
The Aussie's celebration was there for all to see in front of a booing crowd, Kyrgios dropping to the ground and screaming to the heavens as he produced a get-out-of-jail performance to remember.
The players shared a quick handshake before Nadal packed his things and signed autographs, as Kyrgios signalled to the jeering crowd with his finger to his ear.
That winning feeling!
— Sporting News Australia (@sportingnewsau) February 28, 2019
Look at that passion from @NickKyrgios 👏pic.twitter.com/zf5DtnddwV#AMT2019
Kyrgios had won through to the Nadal match after putting up his best performance of the year - at the time, so far - in a crushing win over Italian veteran Andreas Seppi.
Against Nadal, Kyrgios did it all. Medical time outs. Code violations after telling the crowd to shut up. Under arm serving.
ok *NOW* this match has had everything... @AbiertoTelcel @NickKyrgios
— Tennis TV (@TennisTV) February 28, 2019
👀 pic.twitter.com/VpQKXduX0V
And, most importantly, saving three match points to set up the remarkable victory - and still, he had time to sign autographs for fans.
3 hours on-court. 😵
— ATP Tour (@ATP_Tour) February 28, 2019
Still time for the fans. 🥰
👏 @NickKyrgios#AMT2019 pic.twitter.com/APljyS2JyI
Speaking to reporters after the match, Nadal praised Kyrgios: "He is a player who has a huge talent could be winning Grand Slams or fight for the first position in the ranking and something is where it is."
However, Nadal suggested the Aussie has a few things to work on, saying Kyrgios "lacks respect for the public, the opponent and himself”.
“Es un jugador que tiene un talento descomunal podría estar ganando Grand Slams o pelear la primera posición en el ranking y por algo está donde está. Le falta respeto para el público, el rival y hacia sí mismo”... Rafa Nadal sobre Kyrgios @adrenalina pic.twitter.com/ZC1ysaLT2e
— Josefa Gout (@JosefaGout) February 28, 2019
It was Kyrgios' first win over a top five player since he defeated then-No. 3 Grigor Dimitrov in the 2018 Brisbane International semi-finals.
The Australian will now face Stan Wawrinka in the quarter-finals. The Swiss ace fired 32 winners to take down seventh seed Steve Johnson 7-6(5) 6-4.
Wawrinka leads the head-to-head against Kyrgios 3-2, their last clash going the former's way at the Toronto Open in August last year.
Kyrgios became the third Australian to reach the last eight in Acapulco - earlier, John Millman took down Peter Gojowczyk, while an ill Feliciano Lopez's withdrawal saw Alex De Minaur progress.