NEW YORK — If there is a single, overriding lesson to this decade’s developments in American men’s tennis, it is to have a short memory.

“I mean, obviously, right now it’s great,” 19-year-old Jared Donaldson said after his upset of Belgium’s 12th-seeded David Goffin. “During the match, just briefly after, it was great to win. But I mean, it’s kind of on to my next round.”

For Donaldson, it was easy to hurry along after what he called a “really, really special victory.” He is ranked 122nd and needed three wins in the U.S. Open qualifying tournament just to shoulder his way into the main draw before summarily dismissing Goffin, a French Open quarterfinalist this year, 4-6, 7-5, 6-4, 6-0.

But all around Donaldson on Tuesday was the flip side of the need to forget, that familiar sense of U.S. men experiencing what victims at a carnival dunk tank know.

Sam Querrey, just two months after the personal highlight of shocking No. 1 Novak Djokovic at Wimbledon, was sent packing in four sets by Serbian veteran Janko Tipsarevic, who lately has recovered from serious illness and is ranked a humble 250th.

Rajeev Ram, a 32-year-old qualifier more accomplished at doubles, lost to 64th-ranked Brit Daniel Evans. Young hopefuls Michael Mmoh, 18, Denis Kudla, 24, and Christian Harrison, 22, all lost.

That left only Steve Johnson and Donald Young to join Donaldson in feeling more like a hammer than a nail. Johnson, who earlier this month briefly slipped past John Isner to become the top-ranked American at No. 22, had to apply an in-match short memory to recover from a two-set deficit and edge 79th-ranked Evgeny Donskoy of Russia. Young, the 27-year-old former phenom whose many shifts and turns in an up-and-down career reflect general U.S. tennis vertigo, prevailed over No. 78 Jan-Lennard Struff of Germany in four sets.

“Every day can’t be perfect,” Harrison said in a succinct summary of tennis life, constantly swiveling one’s head to follow good versus bad moments, invigorating success versus depressing failure.

“At the end of the day,” said Querrey, who at 28 is ranked 30th after a career high of 17th five years ago, “tennis is great. I love it. But there’s other things in life, and you sort of separate it and move on.”

Harrison, who missed more than two years of competition because of seven operations — abdominal, right shoulder, left wrist, on and on — acknowledged the challenge of dealing with emotional whiplash. “Especially when it’s a week-to-week sport,” he said. “Because, unless you win the tournament, you’re going to lose. So you’ve got to get comfortable with that real quick.

“I think about not being able to play at all. I’d rather be losing in the first round of the main draw and feeling good about coming through the qualies. You always find ways to put it in perspective.

“I look at my phone and the messages from my close friends that, ‘Hey, don’t get down. Keep your head up.’ And I’m, like, they’re right. That’s the way you have to handle it.”

The matches themselves are a microcosm of the process, Donaldson said, because “you run through so many scenarios in your head.” It’s a don’t-think-twice, it’s-all-right mind-set.

Women’s

If Serena Williams’ right shoulder was bothering her Tuesday night, you couldn’t tell by the way she handled Ekaterina Makarova in her opening match of the U.S. Open.

Williams seemed as powerful and dominating as usual, dispatching Makarova, 6-3, 6-3, in a little more than an hour at Arthur Ashe Stadium.

After her Wimbledon victory in July that tied her with Steffi Graf with 22 Grand Slam titles, Williams had a largely inactive and unsuccessful summer with shoulder woes she had been dealing with for a while finally having significant impact. She lost in the third round of the Olympics and pulled out of the Cincinnati tuneup event.

But there she was hammering away at Makarova on Tuesday night. She served 12 aces and four service winners. Only 25 of her 45 serves were returned in play. Combine that with 27 winners, that’s the Serena way. Except she said it wasn’t quite the full-bore Serena serve.

“I didn’t make too many adjustments, I just didn’t hit them as hard as I usually do,” Williams said. “I just went for placement.”