One of the few times Genevieve Beacom can remember boys or men objecting to her playing baseball among them came when she was 11. She was a star pitcher, even at that age, and a boy on another team was so adamant about not facing her that he began to cry.

Was he fearful that he would be humiliated by a girl, or was he opposed to her very presence in the game?

“I think it was a bit of both,” Beacom said with a chuckle in a telephone interview from her home in Australia on Monday.

Either way, she thought it was funny, she said, and struck the boy out. Six years on, she says she never faces incidents like that anymore. Why would she? She has played baseball alongside boys her whole life, and most of the best ones in Australia know her from the circuit. Some are her friends, and the rest are compelled to respect her talent.

That last point was apparent on Saturday in Melbourne when Beacom, 17, became the first woman to pitch in the competitive Australian Baseball League, making her pro debut for the Melbourne Aces in a game against the Adelaide Giants.

Beacom, a rangy lefty with a looping curveball, threw a scoreless inning in relief, demonstrating remarkable poise for her age. The opposing batters, for their part, showed no histrionics or dramatic gestures, and there were no tears. It was just baseball at the highest level in Australia, one of the world’s emerging hotbeds of baseball talent.

“It’s not like Jackie Robinson, who had to face down all that hatred when he broke the color barrier,” said Justin Huber, the general manager of the Aces. “You could see it on the faces of the batters the other night, and in their approach. It seemed natural, like, ‘We’re all here playing baseball and Genevieve is pitching because she can get outs.’

“At the same time, it was an amazing experience.”

Huber, who in his playing days was a catcher who signed with the Mets in 2000 and eventually played for the Royals, the Padres and the Twins, signed Beacom to a player participation agreement this month. That placed her on the Aces’ roster, but without pay, so that she could retain her N.C.A.A. eligibility. Her immediate goal is to play college baseball in the United States, but perhaps even more awaits her.

At 6 feet 2 inches, with a fastball that tops out at 84 miles per hour, a solid changeup and that elliptical curve, Beacom is essentially a typical left-handed prospect who happens to be a woman.

In fact, when it comes to the league she is playing in, her age is nearly as remarkable as her gender. Beacom is still a high school student, attending classes every day and occasionally ducking out early to train or pitch in games.

Huber said there are generally only a handful of 17-year-olds playing in the Australian league, which is a certified off-season league for Major League Baseball. This year, the league canceled its regular season because of the coronavirus, but teams like Melbourne and Adelaide are barnstorming.

Discussing the quality of the competition, Huber said the league was something between Class A and Class AA in the U.S. minor league system, a cut above college baseball. The league has been home to once and future major leaguers, like Jeremy Guthrie, Byung-hyun Kim and Delmon Young, as well as a veritable army of college players.

“College baseball is one of my big goals,” Beacom said. “Every baseball player wants to make it to the majors. But we will see how far the game can take me, whether that is college, minor leagues, the majors. Wherever it can take me, I’m just happy to be on the journey.”

That steadily rising road began when Beacom was 4. Her older brother, Sam Trend-Beacom, 24, played college ball at Lower Columbia College in Longview, Wash. Like so many younger siblings, Beacom tagged along when her brother played youth baseball and soon wanted to play herself. She began with T-ball and advanced to junior club baseball. She loved it, and nothing could stop her — even if some tried.

In Australia, as in so many other baseball-playing countries, girls are often diverted to softball or girls-only baseball leagues. But Beacom managed to resist that kind of categorization. She had become good friends with the boys on her teams and wanted to remain alongside them. Why couldn’t she continue?

“I just enjoyed being around them, and I wanted to stick with it,” she said. “Those guys understood I have a feel for the game and that I actually can compete with them. They still do.”

Beacom did play one year of softball. She hated it and quickly returned to the sport she adores. But the softball thing kept coming back because of a prevailing view that the route to U.S. colleges for girls who play bat-and-ball games involves softball.

At a recent college fair, Beacom met with an adviser and asked about baseball scholarships at U.S. universities.

“He turned to me and said: ‘There’s no baseball scholarships for girls. They play softball, They don’t play baseball,’” Beacom recounted. “But he didn’t know me. He didn’t know baseball is my sport. It definitely happens a lot to most girls, which is quite annoying because a lot more girls are playing baseball now, which is awesome to see.”

Beacom joined the Aces’ elite developmental program in Melbourne several years ago, and that put her on the radar of decision makers like Huber, who has been the general manager of the Aces for seven years. She also pitched junior baseball for the state of Victoria and at an under-16 tournament a year ago for the best 200 boys in the country, where she recorded a 0.00 earned run average. She is on track to play for Australia’s under-18 World Cup team.

Huber said Beacom was once considered one of the top 25 junior pitchers in Victoria, but that was then. She has worked hard and improved rapidly, catching the eye of the Aces’ coaching staff, especially Peter Moylan, the Aces’ manager, who had a 12-season career as a pitcher with the Braves, the Dodgers and the Royals.

After watching Beacom zip the ball in a recent bullpen session, flinging it with good command and movement, Moylan turned to his bench coach, Jon Deeble, and said, “Jon, this girl needs to be on our team.”

“It had nothing to do with boy, girl, woman, man, whatever you call it,” Moylan said by telephone. “It was strictly that I was looking at what she was doing with the baseball, and it was fantastic. I wanted her on my team.”

Moylan also felt Beacom would prosper by working with the pitching coach Graeme Lloyd, a lanky former M.L.B. lefty who won World Series with the Yankees in 1996 and 1998. Huber agreed, and Moylan approached Beacom to ask how she would feel about joining the parent club.

“I couldn’t believe it,” she said. “I was astonished.”

Within days she was pitching in a game, rattled with nerves at first, but able to regain her focus and determination — which impressed Huber the most — to pitch a scoreless inning on 17 pitches.

Her father, Brendan, was awed by the spectacle and the atmosphere in the stadium and beyond. News of his daughter’s achievement swirled the globe and was reported by CNN, The Guardian in England, NBC News, Fox Sports and many other outlets.

“It’s been an incredible journey for Genevieve,” her father said. “The amount of media coverage has been astronomical, and support from everyone pretty much. It’s been terrific.”

Some U.S. independent minor league teams have reached out to Huber to gauge whether she would have interest in signing with them. Huber tells them Beacom has her heart set on college, and he thinks it is the best path for her, too. At least for now.

“But 12 months ago, I didn’t think we’d be talking about a 17-year-old and the Aces in the same sentence,” he said. “In another 12 months, who knows what’s going to happen. The world is at her feet.”