Julien Farel, a Manhattan salon owner, has run a pop-up hair salon at the U.S. Open since 2007. (Darren Carroll/U.S. Tennis Association)

In the maze of hallways underneath Arthur Ashe Stadium, there is a path that winds around drab rooms reserved for news conferences, skirts the peaceful lawn known as the players’ garden, shoots up two flights of stairs and ends at a place where players of all ranking and level of celebrity get treated like Rafael Nadal, Novak Djokovic and Maria Sharapova.

They could even get the same haircut as those stars, should they choose.

The salon at the U.S. Open is just one of the perks offered to players and their entourages during the tournament. Starting the week before the main draw begins, when players competing in the qualifying tournament start flooding Flushing Meadows, salon owner Julien Farel offers world-class haircuts, blowouts, manicures, pedicures and facials in a tiny room tucked in the far corner of the Billie Jean King National Tennis Center.

All services, the likes of which a customer visiting Farel’s 10,000-square-foot spa on Park Avenue in Manhattan could pay hundreds of dollars for, are free of charge.

“The most common thing is haircuts,” Farel said Tuesday, after he rushed from appointments in Manhattan to attend to players in Queens. “It’s a lot of braids before a game, because when you do a braid for somebody like Sharapova or Victoria Azarenka — Sharapova no, but Azarenka has a lot of layers, so you need to lock her hair into the braid to make sure they don’t move. Of course, when you’re doing a braid the important thing is she’s not bothered at any time on court so she can focus on the tennis.

Max Mirnyi was one of the players who got a trim at the salon during the tournament. (Darren Carroll/U.S. Tennis Associationl)

“Then there’s the beauty of it. Athletes, they’re just like you and I, they enjoy looking good, too. The haircut is just a very big part of that.”

Farel has run the pop-up salon at the U.S. Open since 2007. He and his staff of seven, which includes hair stylists and aestheticians, see between 50 and 70 clients on their busiest days of the tournament. The room has just three chairs for hair services, a large table for nail services and a stand with lipstick for those who prefer a little color on court or are dashing out for the night after a match.

The walls are stocked with hair products Farel designed with tennis players in mind — they all have sunscreen protection and hydration for athletes battling humidity. Small canisters of Evian spray are available for those who have dropped by the salon just to cool off after practice.

“It’s amazing how much we do every day,” Farel said. “The first week is the really crazy one, then after people lose there are fewer people. Then I start to become a human again.”

Farel, who counts Ivanka Trump as one of his clients, worked at the salon at Roland Garros in Paris before he moved to New York and eventually drew up a contract with the U.S. Tennis Association. (USTA executives also receive free services from Farel throughout the tournament.)

All four Grand Slams include a salon among their player amenities.

Sabine Lisicki got her nails done by one of Farel’s staff of seven. (Darren Carroll/U.S. Tennis Association)

The Frenchman sees just as many men as women in his work at the U.S. Open, and he counts Nadal and Djokovic as among his most loyal customers. It was Farel who lopped off Nadal’s long hair for the first time in 2010, the first year Nadal won a title in New York, and the Spaniard now makes routine visits to Farel’s Manhattan salon for a cut.

For the men on tour, the salons at Grand Slams are useful stops for players who might not be able to get to their regular barber because of travel.

Jamie Murray, the No. 6 ranked doubles player on the ATP Tour, feels too squeamish about accepting a free haircut to use the salons at tournaments. But he knows plenty of men who stop in just to look presentable on court.

“Hey, everyone loves a freebie,” Murray said, “and mainly, it’s convenient.”

The women have been known to go for more drastic styles at Grand Slam events. American Bethanie Mattek-Sands, known for her ever-changing hair color, was a client of Farel’s. Semifinalist Sloane Stephens notices when players like 20th-ranked Daria Gavrilova show up in the locker room after a visit with Farel.

“First of all, Gavrilova got her hair cut today, super short. I don’t know if anyone saw that, but she looks good,” Stephens said at a news conference last week. “It’s always, like, random. Someone will get their hair colored. You’re like, ‘Okay, more highlights, all right.’ ”

The list of high-profile tennis players who seek out Farel’s salon for a trim and a reprieve from a busy tournament is long, and Farel cherishes his relationship with the USTA.

Still, Farel feels like he has unfinished business at the U.S. Open. There is one player he hasn’t been able to get in his chair.

“We have won the trust of basically every player, and the only one we don’t have is [Roger] Federer,” Farel said with a laugh. “He’s a hard one. Last year we talked about cutting his hair, we talked and talked, and then the next day he lost. He was gone. It happens.”