Sure, there were matches that provided more drama or surprises on Day 1 at Flushing Meadows.
There was 20th-seeded John Isner's comeback from two sets down to edge 18-year-old Frances Tiafoe before a rowdy, standing-room-only crowd at the new Grandstand.
A first-round loss by Rio Olympics gold medalist Monica Puig. French Open champion Garbine Muguruza's complaints about having trouble breathing after dropping the first set of a match she would go on to win in three.
Nothing, though, was as meaningful when it comes to what could go on over the next two weeks as how 14-time major champion Nadal's wrist felt during and after a relatively straightforward 6-1, 6-4, 6-2 victory over Denis Istomin.
The match was played at Arthur Ashe Stadium, where the new $150 million retractable roof remained open under a blue sky, but still offered some extra shade on a day when the temperature reached 90 degrees.
The good news, Nadal said afterward, is that the pain is gone from the part of his body that whips those violent, topspin-heavy forehands that are the key to his success — 14 of his 21 winners came off that wing.
The bad news for Nadal?
He still is working on feeling comfortable hitting down-the-line forehands, in particular, after sitting out — not just zero real matches, but barely any practice, either — from his withdrawal at the French Open in late May to the Olympics this month.
"Not easy to go 2½ months out of competition, in the middle of the season, without hitting a forehand," Nadal said. "I need to have the confidence again with my wrist."
Both Nadal and his coach, Uncle Toni, described the way Rafael changed the way he hits a forehand during the Rio Games to try to avoid pain.
Both said things are improving.
But as Toni noted: "We need a little time."
Istomin, who is from Uzbekistan and is ranked 107th, was not exactly likely to give Nadal much of a test. He entered the day 0-4 against the two-time U.S. Open champion, having dropped 10 of the 11 sets they'd played. He had lost his past 20 matches against top-10 opponents. Plus, he's been dealing with an injured right hamstring lately.
So what did he think of Nadal's play Monday?
"For the first set, I was feeling that he was not hitting hard," Istomin said. "A lot of short balls."
Nadal's summation of his day: "Not very good; not very bad."
Uncle Toni's take? "I hope every day we can play a little bit better."
There were other folks feeling that way, too, for varying reasons. Isner, for one, had to be rather relieved to escape with a 3-6, 4-6, 7-6 (5), 6-2, 7-6 (3) victory over Tiafoe in their all-American matchup.
Tiafoe first built his big lead, let it slip away, then served for the match after breaking Isner for a 5-3 lead in the fifth set. But Isner broke there.
"Probably played the best return game I played all match," Isner said. "Even though I was pretty haggard out there, I got a jolt of energy when I got it back to 5-4."
And then the winner of the longest match in tennis history — 70-68 in the fifth set at Wimbledon in 2010 — took advantage of the U.S. Open's fifth-set tiebreaker to close it out in about 3½ hours.
Afterward, an exhausted Tiafoe leaned into Isner's chest when they met at the net.
"The last thing I heard him say is, 'Don't let this get you down,'" Tiafoe recalled.
Puig was seeded at a Grand Slam tournament for the first time, at No. 32, and was back on court a little more than two weeks after becoming the first athlete representing Puerto Rico to earn a gold medal in any sport at any Olympics.
"A lot of pressure," she said. "A lot of expectation."
She exited the U.S. Open quickly, beaten 6-4, 6-2 by Zheng Saisai of China.
"You know what?" Puig said afterward. "This isn't going to be the last of me."