NEW YORK — Before taking on Marin Cilic, the 2014 U.S. Open champion, in the third round, Jack Sock acknowledged that as of a couple of years ago, simply making it that far would have made him, to use two of his words, “satisfied” and “excited.”

Now Sock, a 23-year-old American, wants more. He thinks his game and mindset are ready for deep Grand Slam runs. And the way he overwhelmed the No. 7-seeded Cilic, 6-4, 6-3, 6-3 in a little more than 11/2 hours Friday to reach the fourth round at Flushing Meadows for the first time, who would doubt him?

Jack Sock of the United States reacts Friday after defeating Marin Cilic of Croatia in straight sets to reach the fourth round of the U.S. Open for the first time. Associated Press/Seth Wenig

“Just all around, I think I’m putting things together, better and better,” said the 26th-seeded Sock, who celebrated with a racket-as-foil jousting move in tribute to his friend and fellow U.S. Olympian, bronze medalist fencer Miles Chamley-Watson. “I feel more confident out there in everything I’m doing.”

Against Cilic, who followed up his title with a semifinal appearance a year ago, Sock won all 14 of his service games, never facing so much as one break point. Not much of a surprise there on a hard court for a guy whose game is best known for two parts – “‘serving and forehand’ is what I hear all the time,” he said with a hint of a smirk.

But on this windy afternoon, Sock showed off other improving parts of his repertoire. Sure, he delivered 10 forehand winners, but he also produced four on the backhand side (Cilic only had two). And as good as his serving was, with a top speed of 138 mph and 86 percent of first-serve points won, Sock’s returns were in fine form, too: He broke Cilic four times.

“He’s a very dangerous guy in these kind of conditions,” Cilic said, “where the ball is coming off pretty fast, off the court.”

Sock’s second career appearance in the fourth round at a Grand Slam tournament – the other came at the 2015 French Open on clay – will come against No. 9 Jo-Wilfried Tsonga of France. Tsonga, the runner-up at the 2008 Australian Open, moved on Friday with a 6-3, 6-4, 7-6 (4) victory over No. 23 Kevin Anderson.

Other men into the Round of 16 included No. 1-seeded and defending champion Novak Djokovic, No. 10 Gael Monfils, No. 24 Lucas Pouille and 2006 Australian Open finalist Marcos Baghdatis, who ended the career-best showing of American qualifier Ryan Harrison by beating him, 6-3, 7-6 (4), 1-6, 6-1.

At night, Rafael Nadal produced a spectacular ‘tweener lob with his back to the net on the next-to-last-point of his 6-1, 6-4, 6-2 victory over Andrey Kuznetsov. Nadal returned to the fourth round at the U.S. Open for the first time since winning the 2013 title.

Friday’s most stirring turnaround came when No. 8 Madison Keys of the U.S. was down 5-1 in the third set before edging Japanese teenager Naomi Osaka, 7-5, 4-6, 7-6 (3).

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