Rafael Nadal, in his comfort zone, advances to US Open quarterfinals

Nadal mesmerizes the crowd with dazzling performance (2:17)

Rafael Nadal defeats Marin Cilic in four sets with several unbelievable plays to advance to the quarterfinals of the US Open. (2:17)

NEW YORK -- Rafael Nadal hasn't incurred the wrath of the fans by mistreating a ball kid, nor shot them a central digit the way Daniil Medvedev did on Louis Armstrong Stadium on the boisterous first Friday evening of this US Open. He hasn't jousted with a heckler, as Novak Djokovic did during his practice session earlier that afternoon, nor defended himself against charges of favoritism the way Roger Federer was obliged to do after his third-round success.

Nadal has avoided dramatic interludes of any kind during this first, tumultuous, seed-busting week of the US Open. He has gamboled in the sunshine, taking care of business in familiar if somewhat muted fashion with nary an anxious glance toward his support team, nary a leaping uppercut accompanied by the war cry, "Vamos!" He did have to work on Labor Day, dutifully wearing down former US Open champion and No. 22 seed Marin Cilic in 2 hours, 49 minutes 6-3, 3-6, 6-1, 6-2.

During his third-round mastery of South Korea's Hyeon Chung, a stray moth danced around his ankles as he prepared to serve. Instead of squishing it, Nadal gently shepherded the critter toward the sideline with the face of his racket. He picked up a speck of debris on the court and handed it off to a ball boy as if he'd read the stern memo about keeping his workspace clean.

Though diligent as ever, the 33-year-old, two-time champion is playing like he hasn't got a care in the world, and maybe he doesn't. With Djokovic out of the draw and Federer still very much in it, this might not officially be Nadal's tournament to lose. He has powered his way into the quarterfinals, that dream final of Federer vs. Nadal -- it would be their first meeting ever in this tournament -- beckoning on the horizon. Nadal can't face a seed higher than No. 13 Gael Monfils, whom he has beaten in 14 of 16 matches, including a four-set win here in 2009.

This much is already certain: Nadal is in a far happier and more comfortable place at this US Open tournament than he has been in on many Grand Slam occasions. That's mostly because he has won yet another career-threatening struggle with injury, and he has navigated the challenges of recovery. He's blasting the rust off his game and doubts from his mind.

"The first three, four months of the season [were] very hard -- too many issues again," Nadal said, referring to injuries that continued to hamper his training efforts. His fortunes began to change in Barcelona, although Nadal uncharacteristically lost on his beloved clay there, and also in Madrid. His 12th win at the French Open accelerated his turnaround. It was followed shortly by a semifinal at Wimbledon and a win on the hard courts of Montreal.

"I was able to fix the body and play more or less with freedom of movements," he said. "That gave me the chance to compete at the highest level again. And most important thing ... to enjoy the sport."

Nadal said his recent history gives him "positive" feelings and memories to draw upon. Coming into this event, he could use the reinforcement. Last year, he was compelled to quit his semifinal with Juan Martin del Potro after two mostly agonizing sets, his chronic knee tendinitis overriding his famous combative spirit. He left his postmatch news conference abruptly when he was overcome with emotion and teared up.

"Tearing it up" is a better way to describe Nadal's performance against Cilic. After a slow start, the 30-year-old Croatian was soon crushing the ball with the same ferocity as Nadal. Cilic has a serve that can make babies cry. He backed it up with forehand blasts and soon found himself dictating the nature of the points. Nadal had clearly overestimated his ability to win points from deep in his own backcourt. Nadal didn't exactly panic, but a few alarm bells began to ring in the mind of the three-time US Open champion when Cilic took the second set. Nadal realized he needed to rethink his strategy.

"For some moments in the second set, too many points were in his hands," Nadal admitted afterward. At 1-1 in the third set, Nadal decided to move up and take Cilic's second serves on or near his own baseline and generally play from inside the court whenever possible. "Something need to change, and I did it, not letting him take the points in his hands."

Cilic was also unable to invest the same amount of energy in the rallies as the match wore on.

Most of the high seeds in the half ruled by Nadal have been bulldozed out of the way: No. 4 Dominic Thiem, No. 6 Alexander Zverev, No. 8 Stefanos Tsitsipas and No. 9 Karen Khachanov -- all gone.

Nadal's fortunes on hard courts have usually rested on his willingness to abandon the dogged defensive posture that has earned him those 12 French Open titles and the moniker "King of Clay." The perceived wisdom is that Nadal's success on hard courts hinges on serving with a degree of command and variety that he doesn't necessarily need on clay, and on stationing himself up close to or inside the baseline in rallies -- a tactic that enables him to be more aggressive and to employ his excellent volley.

But implementing those tactics, as he did on Monday evening, isn't simply a matter of Nadal having the will to overcome his default, defensive posture. "I don't have a different style of play [for hard courts]," the three-time US Open champion said. "I play my style sometimes better, sometimes worse."

The comment explains why Nadal at times can look as if he's at a loss on hard courts, while on other occasions -- such as these days -- he looks deadly. The aggressive tactics come easily only when he's firing on all cylinders. Then, he can effectively push his opponent around on the court, taking away time and forcing him back to leave him vulnerable to those heavy approach shots and follow-up, angled volleys. Most of the time, Nadal falls back on his defensive posture only when he's not dialed in.

Chung, the 23-year-old South Korean who's fighting his way back from back and foot injuries, can attest that Nadal has been dialed in. Chung found it difficult to stay in rallies, but he was also aware that Nadal would take advantage of any short ball. Chung said Nadal played more aggressively than in their two previous meetings (both wins for Nadal). "I think so, because I have a lot of pressure from him. It's tough to play good baseline [tennis]."

Nadal has accumulated the best winning percentage on hard courts this year: 17-2 for 89%. He has taken great strides since hobbling away from this event last year, the prelude to yet another long sabbatical. Nadal pulled the plug on his season after the US Open and was unprepared for the heightened demands of playing a big-three rival in a Grand Slam. Nadal impressed as he slashed his way to the Australian Open final, but Djokovic walloped him in the title match 6-3, 6-2, 6-3.

Earlier in the week, Francisco Roig, who co-coaches Nadal with Carlos Moya, told the ATP media team that Nadal is feeling "more complete" now on hard courts, has boosted the speed of both first and second serves and approaches the net with greater confidence.

The stats from Nadal's win over Cilic bear his coach's analysis. Nadal unloaded 38 winners, a testament to his aggressive mindset, although Cilic was almost equally bold (33 winners). The famed Nadal consistency was in play, the No. 2 seed making just 26 unforced errors to a hefty 40 by Cilic. Although Nadal won only one more of the rallies lasting at least nine shots, he was superb in rallies lasting five to eight shots, which are the bread and butter of aggressive baseliners. They might not serve and volley, but they are always looking to force the action and end points.

"Rafa gained praise and found success by engaging in drawn-out affairs and wearing down opponents," Roig said of the past. "These days, he's dictating play more. I think he is realizing the value of building up a point with a more pointed attack, and he's evolving into a more well-rounded player. When you're sitting back in a comfort zone, chances are the opponent is settling down and into a groove, as well."

Nadal has settled into a comfort zone in a different, more productive way at this tournament. He has found as clear a path to the title as anyone in his shoes could hope to enjoy.