It is not just the aspiring teenage players themselves who are providing a glimpse into the tennis future in Flushing Meadows this week. Coming soon could be an acceptance of an on-court coaching experiment being tested in the U.S. Open’s junior tournament.

The trial, debuted in the qualifying rounds and now restricted to the 18-and-under competition, allows coaches to speak with players — or communicate via hand signals — during any break in play.

Theoretically, this is a revolutionary development, given the sport’s doctrine of self-reliance. In fact, it is one way to solve the problem of technically illegal coaching from the stands that is widely acknowledged.

Since 2009, the women’s tour has allowed players to summon their coach, one time per set or during an opponent’s medical break, for an on-court tutorial during changeovers. The exchanges can be heard during televised matches, a clear marketing strategy. The men’s circuit has no such provision. Nor do the four Grand Slam events, which are governed separately.

Elysia Bolton, the 17-year-old from Cold Spring Harbor who advanced to the juniors’ quarterfinals after upsetting No. 2 seed Marta Kostyuk of Ukraine, said she benefited from the new directive right away. “I hit a rut in the first set [of her first match] and my coach was able to talk me out of it,” she said. “I thought it helped a lot. I like it a lot.”

Not everyone does. During her second-round upset loss, 15-year-old No. 1 Junior seed Whitney Osuigwe of Bradenton, Florida, could be seen rolling her eyes as her coach, Eric Kortlund, attempted to offer advice.

“I do use the WTA coaching,” said the 91st-ranked Jennifer Brady, who was eliminated in the fourth round of the main draw. “I guess it’s different for everybody, but regardless of what your coach is telling you, it comes down to you. I feel like you should be able to figure things out on your own.”

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Nicole Gibbs, the 127th ranked player who took advantage of the pilot system to help her through qualifying into the main draw, nevertheless cautioned that “my coach is not inventing a new way to play tennis. He’s just kind of reminding me of the things we’re working on in training. And even if I don’t talk to him, I pretty much know what he’s going to say: ‘Look for your forehand. Play aggressive. Move forward.’ ”

Gibbs did say she “vastly” favors the communication from the stands over the women’s tour method. “Because when you have a minute and a half to blurt out everything that you’re stressed about and your coach has to fix things,” she said, “it lends itself to not great communication. If there is coaching, I’d prefer it to be the way it’s been done here.

“You can communicate. And he can signal me from the other side because you don’t want him to shout across the court, ‘Your forehand is terrible right now.’ ”

Many players argue that technical and strategical guidance is neither helpful nor easily processed during play. “It’s more of what state I’m in,” said Poland’s Magda Linette, the 72nd ranked player who lost to top seed Karolina Pliskova in the first round. She found, on the women’s tour, the visits with her coach were basically “something to calm me down. Something like, ‘Shhhhh.’ Usually the mental.”

The most often told example of violating the in-match coaching prohibition is the tale of Maria Sharapova’s father and coach, Yuri Sharapov, signaling her to eat a banana during her championship victory in the 2006 Open against Justine Henin-Hardenne. (If, in fact, that was coaching.)

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Steve Flink, the tennis historian who this summer was inducted into the sport’s Hall of Fame’s “contributor category,” is among those convinced that the non-coaching rule long has been violated routinely. His suggestion is to apply the Davis Cup practice to both men’s and women’s tours and the Grand Slam — having the coach sit next to the players’ chair on court and be constantly available.

In the meantime, coaches and their Open juniors might want to work out hand signals (not susceptible to opponents or Boston Red Sox skulduggery.) But Bolton said she and her coach hasn’t gotten past “a fist pump. Which means, ‘Let’s go.’ ”