Rising Australian tennis star Maya Joint has forfeited the bulk of her $210,000 prize money for making the second round of the US Open in order to remain eligible for college in the USA.

Having made it through qualifiers, Joint shocked German Laura Siegemund to win her maiden grand slam main draw tie at Flushing Meadows a fortnight ago. She lost to Madison Keys in the second round, but still climbed to a career-high No.111 in the singles rankings as a result.

However, Joint was forced into choosing between the biggest prize fund of her short career or her eligibility to attend college because National Collegiate Athletics Association (NCAA) rules forbid college students from accepting prize money beyond coverage of “actual and necessary” expenses.

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The American-born 18-year-old – who in 2023 switched allegiance to Australia given her father’s nationality – missed the first week of classes in a psychology degree at the University of Texas because she was competing in New York.

Another college student, Reese Brantmeier, is currently suing the NCAA over those rules.

Joint joined the action on Saturday, seeking a preliminary injunction that would allow her and other athletes to claim prize money until a final ruling is made.

Under the US Open rules, Joint had to inform the US Tennis Association if she would accept or forfeit the prize money by the end of the tournament, which was Monday morning (AEST).

The court did not rule in time, which meant Joint had a decision to make. She chose her education.

“The money is gone … it’s immensely disappointing,” her attorney Jason Miller told The Washington Post.

Joint and Miller had approached the USTA for an extension on the deadline on the prize money decision, which was rejected.

“While we understand and are empathetic to Ms Maya’s situation, it would be unfair and inequitable to change our practice or grant exceptions to these rules in the middle of a tournament after others have already made their decisions and submitted their paperwork based on the long standing practice,” a USTA spokesman said.

Joint can claim enough to cover her expenses in competing in the tournament, including accommodation, coaching fees, meals and other logistics. Should the judge grant the injunction now, Joint has no way of reclaiming the rest of the forfeited money.

Joint had said ahead of the tournament she would likely forfeit the money anyway, but was hopeful the Brantmeier case would have a ruling before she had to make a decision.

NCAA allows high-schoolers and amateurs to claim up to $15,000 (US$10,000) a year in prize money. Joint had already enrolled at the University of Texas before qualifying for the US Open began, meaning she can only claim the prize money to cover expenses.

Generally speaking, college athletes in the USA do not earn a formal salary. However, some – particularly in American football – have signed six-figure endorsement contracts. NCAA college football television rights generated $1.3billion in revenue in the 2022 financial year.