Rafael Nadal hits a return to Marin Cilic at the US Open on Monday. Photo: IC

Rafael Nadal ramped up his quest for a fourth US Open title Monday with an impressive win over 2014 champion Marin Cilic to advance to the quarterfinals while Alexander Zverev slumped to a four-set defeat.

Second seed Nadal - the winner at Flushing Meadows in 2010, 2013 and 2017 - produced some electrifying moments of brilliance to end the challenge of Croatian 22nd seed Cilic 6-3, 3-6, 6-1, 6-2.

After barely breaking a sweat in reaching the last 16, a run that included a second-­round walkover, Nadal stared down his stiffest test so far to surge into a quarterfinal meeting with Argentine 20th seed Diego Schwartzman.

The Spaniard exchanged the first two sets with Cilic but grasped control by breaking for 3-1 in the third, a series of dazzling winners drawing an animated fist-pump from golf legend Tiger Woods at Arthur Ashe Stadium.

Nadal reeled off nine games in succession across the third and fourth sets and 12 of the final 15 to nail down a 40th Grand Slam quarterfinal appearance, nine of which have come at the US Open.

"The emotions I have when I play here are impossible to describe. I love the sport and feel very lucky to still be playing tennis here," Nadal said. "It's a huge honor playing in front of all of you and playing in front of Tiger is a very special thing. I always say I don't have big idols but one idol is him and I always try to follow him."

Nadal's path to the final sees him take on Schwartzman next after the 1.70-meter ­Argentine chopped down sixth seed Zverev.

Zverev rolled through the opening set against Schwartzman under the roof on Ashe during a rainy afternoon session, but he lost his way to go down 3-6, 6-2, 6-4, 6-3.

The German was enjoying his deepest run in New York but committed 17 double faults and 65 unforced errors and received a point penalty for swearing as Schwartzman advanced to a second US Open quarterfinal in three years.

"Generally my season so far has not been the best," said Zverev, who has reached just two quarterfinals in 18 Grand Slam appearances. 

Zverev said he was hindered a "very swollen" back and right hip following a fall in his previous match. "I had a lot of chances which I didn't use early in the match. He kind of ran away with it."

Zverev lost his serve three times during the second set but appeared to have steadied himself when he moved a break ahead at 3-2 in the third, only for Schwartzman to wrest the momentum back in his favor after a lengthy sixth game.

Matteo Berrettini became just the second Italian man to progress to the US Open quarterfinals, 42 years after Corrado Barazzutti's run to the last four in New York.

Berrettini, the 24th seed, eased to a 6-1, 6-4, 7-6 (8/6) win over Russia's 43rd-ranked Andrey Rublev to reach the last eight at a Grand Slam for the first time. 

Berrettini went one step further than his run to the last 16 at Wimbledon in July, where he was beaten by Roger Federer.