FILE - In this June 10, 2018, file photo, Spain's Rafael Nadal reacts while holding the trophy after defeating Austria's Dominic Thiem in the men's final match of the French Open tennis tournament in Paris. Nadal, a French Open champion yet again a week past his 32nd birthday seems to stay forever young. (AP Photo/Thibault Camus, File)
FILE - In this June 10, 2018, file photo, Spain's Rafael Nadal reacts while holding the trophy after defeating Austria's Dominic Thiem in the men's final match of the French Open tennis tournament in Paris. Nadal, a French Open champion yet again a week past his 32nd birthday seems to stay forever young. (AP Photo/Thibault Camus, File) Credit: Thibault Camus

Boris Becker earned the nickname “Boom Boom” for his massive serve. He dove for volleys with the abandon of a child jumping in mud puddles. And when he won his first Wimbledon championship in 1985, he wasn’t much older than a child.

At 17, Becker made history as the youngest man to win a Grand Slam championship. But he looked more boy than man that day at the All England Club as he thrust his arms skyward in triumph, a huge smile spreading over his plump, rosy cheeks and grass stains covering his once-white shorts.

For all the brashness of Becker’s game, he wasn’t the only precocious player of his generation. In the nine-year span from 1982 to 1990, five teenagers combined to win nine Grand Slam titles in men’s tennis (Mats Wilander, Stefan Edberg, Michael Chang and Pete Sampras, in addition to Becker).

In the 28 years since, it has happened just once: In 2005, when 19-year-old Rafael Nadal won the first of his 11 French Open titles.

The disappearance of teenage men’s champions from the sport’s four majors is the result of multiple factors — not the least of which is the enduring excellence of Nadal, now 32, and 36-year-old Roger Federer. Currently ranked No. 1 and 2 in the world, respectively, they have combined to win 37 of the last 61 major titles, dating from 2003. And they’re showing no sign of relenting — instead, getting wiser about how to manage their bodies and careers — which partly explains how they’ve hogged the past six consecutive Grand Slam titles, taking turns hoisting the trophy at each. (Nadal won the 2018 and 2017 French Opens, as well as the 2017 U.S. Open; Federer claimed the 2018 and 2017 Australian Opens, as well as Wimbledon in 2017).

Federer will be favored when he opens pursuit of a ninth Wimbledon title today at the All England Club — even though he’s now a father of four and nearly 20 years older than Becker was in 1985.

“Kids can’t beat grownups anymore the way they used to,” tennis analyst Mary Carillo put it bluntly, summing up the myriad factors behind the generational shift that’s so striking at the top of the men’s game.

For one, changes in the technology or rackets and strings have sped up the pace of play dramatically. Moreover, changes in the way elite athletes train, eat and recover, aided by the services of full-time trainers, coaches and hitting partners.

All told, the evolution of tennis in recent decades has put Grand Slam titles out of reach for even exceptionally gifted teens, particularly in the bet-of-five-set format required to win a men’s major.

But that’s not to declare teenage tennis champions extinct, argued Patrick McEnroe, who competed in the era of Wilander, Edberg and Sampras and has devoted his career since to developing the next generation of players.

“Five years ago, I would have said it will never happen again,” said McEnroe, 51, in a telephone interview. “But now, I see what’s happening at the junior level. These kids are now training in another way, at another level, 12 months a year to be prepared at 19 to physically compete.”

Among the teens who have caught his eye, and that of many other tennis analysts, are 19-year-olds Denis Shapovalov of Canada and Stefanos Tsitsipas of Greece.

The left-handed Shapovalov is the youngest in the top 100, currently ranked 26th, and attacks the game with crowd-pleasing, high-risk gusto. He first earned international notice by toppling Nadal and 2009 U.S. Open champion Juan Martin del Potro at the 2017 Canadian Open, showing impressive poise at 18.

Tsitsipas arrives at Wimbledon with a career-high ranking of 35 and career-high confidence, to boot.

Carillo is intrigued by an even younger Canadian, Felix Auger Aliassime, a speedy 17-year-old who has emerged as a star on the Challenger circuit.

But it is a tall order, both physically and mentally, to win seven best-of-five-set matches in the current era against a 128-player field almost exclusively composed of grown men.

“I’m not gonna say it’s impossible,” former pro Brad Gilbert said. “But it’s a lot more difficult [today], with the physical demands and the length of time it takes to get to where you can handle that.”

For decades, Grand Slam championships could be won on tennis skill alone. No longer, McEnroe explained. Certainly, a broad repertoire of shots and court-savvy remain essential. But so, too, are speed, strength, stamina, along with sport-specific qualities such as explosiveness, agility and flexibility.

“The game is way more physical now that it has ever been,” McEnroe said “Back in the days of Becker and Mats and those guys, you could be a great tennis player and you could break through if you had great skills with the racket and knew how to maneuver the ball. Nowadays, you could be the most amazing tennis player, but until you have the physicality to go along with it, you have no chance to win a major tournament.”

The proof is on video, verified by a quick YouTube scan of highlights of the great Grand Slam matches of 30, 40 years ago. The five-set 1980 Wimbledon final between Borg and John McEnroe is breathtaking for its strategy and shot-making. But the pace is so slow and deliberate, compared to today’s rapid-fire exchanges, that it almost looks as if it’s taking place under water.

Given the current premium on athleticism, it’s not surprising that many promising juniors take a more strategic approach to their development: competing a few rungs below, on the Futures or Challengers circuit, or playing college tennis while their bodies develop before plunging in against 30-somethings.

“When I turned pro in 1982, it took 15 minutes to be top 100,” recalled Gilbert, now an ESPN analyst. “It happened very quickly: Boom! You were playing pro tennis. Now, kids that are 15, 16 aren’t rushing to play on the pro tour; they’re working on their games. And now when a kid turns pro, it takes two or three years to become top 100.”

Exacerbating the physical divide between promising teens and established pros is the very real-word financial divide. Wilander, 53, a former No. 1 who won seven Grand Slam titles, was quick to point out the difference money makes in pros’ preparation.

“It sounds shallow, but it’s not; it’s a huge difference,” said Wilander, who works as a tennis analyst and mentors promising juniors at College Park’s Junior Tennis Champions Center. “In our day, people couldn’t afford to have a physical trainer, a physical therapist a tennis coach. Lots of guys just traveled on their own. We made good money, don’t get me wrong, but not enough to spend $50,000 a week on three or four different people to take care of our body all the time. So it’s tough today, until you can break through and make good money and surround yourself with the team you want.”

And with players competing longer, it’s tougher still for youngsters to break into the top 30 or 40 — or even top 100. Tennis players’ careers weren’t as long in 1970s and ’80s. Borg retired at 25, giving way for others to ascend. John McEnroe peaked between age 22 and 25.

Moreover, Federer and Nadal weren’t standing in the way of every aspiring youngster.

Says Wilander: “Federer and Nadal are obviously the two best players of all time in terms of dominating in two generations. I’ve never seen two players with that much drive, talent and passion for the spot. I think they have fueled each other in many ways. That’s the real reason we don’t have teenage winners.”