NEW YORK (AP) — Jarrad Magee was about halfway through his 18-hour shift stringing rackets to the exacting specs of the U.S. Open's top players this week when he looked up at the TV and saw temperamental star Nick Kyrgios smashing his handiwork into the court.

"Yeah, it was one I had just done. ... He does that a lot," Magee, from Sydney, Australia, says with a shrug. "What are you going to do?"

Being part of the elite team of 16 stringers who toil under the stands of Arthur Ashe Stadium is a job that comes with frustration, deadline pressure and little thanks. But their reward is being considered one of the best at what they do, and taking pride in seeing their work play out on the game's biggest stage.

Over the three-and-a-half weeks from qualifying through the finals, their glass-enclosed shop near the players' lounge becomes a factory floor. Rows of stringers who work from 7 a.m. until the last ball is struck rarely look up from their machines amid the constant pop-pop-pops of old strings being cut out and the zzzripps of new strings being threaded in.

String jobs that would take the average stringer an hour are cranked out in 20 to 25 minutes, with rush jobs turned around in as little as 12. In the early rounds, when the draws are still flush with players, the shop can routinely string 500 rackets a day (514 is the record) and more than 5,000 for the full run of the tournament.

"It is not a glamorous life," acknowledges Ron Rocchi of Wilson Sporting Goods, who has managed the stringing at Flushing Meadows for 11 years and recruited stringers from the U.S., Australia, South America, Europe and Japan. "It's long hours, high stress. ... But they do it because they care about players and want them to do a good job. And when they go back to their homes, they stand out because they are one of the best stringers in the world."

The massive volume is a function of some undeniable realities of modern tennis. Strings have become perhaps the most important piece of equipment in a player's arsenal, particularly the polyester monofilaments that generate a "deader" feel but noticeably more spin, allowing them to take a full whack at the ball and still keep it in the court.

The importance of strings has led players to become endlessly obsessive about them, tweaking the tension based on the weather, the speed of the surface and even a particular opponent. Getting the optimum tension means getting the string job done as close to match time as possible.

Rocchi says that to achieve just the right tension at just the right time, it has now become de rigueur among players at major tournaments to get all of their rackets freshly restrung for every match.

"Juan Martin del Potro drops seven for each match. Jack Sock, six, seven, eight. Kei Nishikori will string eight or nine," says Dustin Tankersley , a veteran member of the team from the Dallas area.

And string jobs that are more than a day old simply won't do. So if a player advances in the tournament or even if rain washes out play, as happened earlier this week, stacks of rackets, most of them untouched, will be sent back to the stringing room to be strung again.

"You end up stringing the same rackets over and over," Magee says of the Sisyphean aspects of the job. "But you can't really blame the players. They have a lot of money on the line. They want it like they want it."

For Monica Niculescu, the 57th-ranked woman who advanced to the third round Thursday, she likes her strings loose, as low as 21 kilograms (46 pounds) to achieve maximum spin on her unusual forehand slice. She, too, has changed up her tension demands to the U.S. Open shop to adjust for slightly cooler weather.

"Obsessed, not really," she said. "But every match I string it."

The ultimate request is the "on-court" job, stringing's equivalent of an emergency room code blue. A player who doesn't like the feel of his racket during a match orders new strings in real time, which involves having a ballkid run it into the shop to be restrung and then back to the court — a turnaround that averages 16 minutes. It's been done in as little as 12.

It culminates in what has become the ultimate boss move in pro tennis, when the player casually grasps the handle of the pristinely strung racket from the ballkid and pulls it out the clear plastic bag.

"That is cool," Rocchi says.

So do the players appreciate all this hard work?

"We really don't get many complaints," Tankersley says. "We don't get that many thank yous, either."

Such kindnesses are so rare that they stand out. Tankersley remembers a few years ago when Rafael Nadal dropped off his rackets and then walked into the stringing room.

"He could easily have walked by us and not said a word. But he said, 'Thanks guys, I'll see you tomorrow.'" ... That was nice."

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