If that wasn't the shot of the match Monday, then surely this was, a couple of points later: a crosscourt backhand passing winner off an overhead by his opponent, 2014 champion Marin Cilic, good enough to earn a yell and four fist-pumps from Nadal -- along with an animated uppercut from Tiger Woods at Arthur Ashe Stadium. Then again, maybe it was the sprinting, sliding, bend-it-around-the-net-post forehand winner to get to match point, which Woods loved, too.
Nadal is looking healthy and hungry at Flushing Meadows so far, and he quickly broke things open against Cilic by seizing nine consecutive games for a 6-3, 3-6, 6-1, 6-2 victory in the fourth round.
Asked to explain that shot on the penultimate point, Nadal chuckled a bit and said: "It's easy to describe and difficult to make.''
"I hit it well,'' Nadal said, "but to hit that spot, of course you need some luck.''
Nadal, 33, seeded No. 2, reached his ninth quarterfinal in New York and 40th at all major tournaments. He retired from his 2018 semifinal at the US Open with a knee injury and will try to get back to the final four by beating No. 20 Diego Schwartzman in the quarterfinals. Schwartzman advanced earlier Monday by eliminating No. 6 Alexander Zverev 3-6, 6-2, 6-4, 6-3.
Nadal is attempting to claim his fourth US Open championship and 19th Grand Slam trophy overall. Roger Federer holds the men's record of 20 majors. The rivals never have played each other in New York; they could meet in only the final this year.
Against Cilic, who entered Monday with a 5-0 mark in fourth-round matches at Flushing Meadows, everything turned shortly after Nadal ceded a set for the first time in the tournament. As it is, he had played only two matches before this one, because his second-round opponent, Thanasi Kokkinakis, withdrew with a bad shoulder.
At 2-1 in the third set, with Cilic serving, Nadal came up with that no-look volley to begin things. After Cilic missed a shot, Nadal's big backhand made it love-40. One double fault later, that game was over -- as, essentially, was the match.
Cilic simply never recovered.
They would go on to play for about another hour, and he managed to grab just two more games.
Earlier Monday, Schwartzman took full advantage of Zverev's 17 double faults to reach the quarterfinals at Flushing Meadows for the second time.
Zverev's serving problems have dogged him for months, and they came back in force against Schwartzman. The lanky German lost his serve eight times, won just 32% of second-serve points and amassed 65 unforced errors. He also was hit with a point penalty for swearing in the final set to put Schwartzman up 5-2.
"My first serve is still fine. My second serve needs to be worked on,'' Zverev said. "But I'll deal with it.''
The 20th-seeded Schwartzman, meanwhile, went about his steady baseline and retrieving game, taking the majority of long rallies in a match when some points went on for as many as 35 strokes.
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Berrettini won 14 of his 15 service games and more than 80% of his first-serve points, and he ripped 37 winners, including a deftly angled volley on match point to close it out.
It's his deepest run at a Grand Slam event after reaching the fourth round at this year's Wimbledon. Berrettini became the first Italian man in the U.S. quarterfinals since Corrado Barazzutti 42 years ago.
Berrettini, who is from Rome, credited advice he has received from Barazzutti, now Italy's Davis Cup captain; Berrettini said they speak to each other every day.
Berrettini also gets frequent text messages from another past Italian star from decades ago, 1976 French Open champion Adriano Panatta.
"I have to say,'' recalled Berrettini, "he's the first one that told me, 'You're going to serve, like, 220 kph [135 mph].' I was 16 when I heard that. I was, like, 'I don't know. [But] if you say that, I'm going to trust you.''"
Next up for Berrettini is 13th-seeded Gael Monfils of France.
Monfils quickly advanced to his third US Open quarterfinal, needing less than an hour and a half to dispatch Pablo Andujar 6-1, 6-2, 6-2.
Monfils, 33, was never seriously threatened against the 70th-ranked Andujar, ripping 34 winners to just four from his opponent and never losing his serve.
For Monfils, Flushing Meadows gives him another chance to deliver on the potential of one of the game's great shotmakers and showmen. Though he has now advanced to at least the quarterfinals of nine Grand Slam tournaments, he has never gone further than his semifinal showings at Roland Garros in 2008 and the US Open in 2016.
The Associated Press contributed to this report.