Naomi Osaka was fined $15,000 at the French Open for skipping a post-match news conference after her first-round victory Sunday - and threatened by all four Grand Slam tournaments with stiffer penalties, including being defaulted, if she continues to avoid meeting with the media.

The fine will come out of Osaka’s prize money and was announced in a joint statement from the president of the French tennis federation, Gilles Moretton, and the heads of the other majors.

Osaka returned to Roland Garros after skipping the trip last time, turning in a mistake-filled 6-4, 7-6 (4) victory over 63rd-ranked Patricia Maria Tig at Court Philippe Chatrier on Day 1 in Paris.

Other results perhaps were more newsworthy than a straight-set win by the No. 2-ranked Osaka - that’s certainly the case for U.S. Open champion and two-time French Open runner-up Dominic Thiem’s 4-6, 5-7, 6-3, 6-4, 6-4 loss to 68th-ranked Pablo Andujar - but the events that unfolded after the Japanese superstar’s match were of high interest.

That’s because Osaka vowed in a Twitter post Wednesday, and then kept that promise Sunday, to stay away from the standard back-and-forth with the media in Paris, the sort of thing athletes in various sports do as a matter of course. She framed it as a mental health issue, saying that it creates self-doubt to have to answer questions after a loss.

Players at Grand Slam tournaments are required to attend news conferences if requested to do so; refusing is punishable by fines of up to $20,000.

That, of course, is not a big deal to Osaka, the world’s highest-earning female athlete thanks to endorsement contracts worth tens of millions of dollars annually.

“It’s her own choice. I think she's capable of making her own choices and obviously she will do always what’s best for her,” Tig said.