Tennis players receive threatening messages, including photos of a gun, demanding they lose matches

"They said they knew where my family lives, what cars they drive and that they had their phone numbers. They even sent photos of my family members and a picture of a gun."

The message Udvardy received said the culprit or culprits "know everything about your family and you" and were "ready for war if necessary, and we won't hesitate to send them to your mother's house to kidnap her until she returns the money we would lose because of your disobedience."

The message Stefanini received was eerily similar.

Stefanini, too, told the WTA about the situation, and she also received boosted security.

"I'm making this video and explaining what happened because I don't think it's right to put me under this pressure and unease before a match," Stefanini said.

Udvardy said the messages are "not normal."

"Even as athletes or public figures, it's not acceptable to receive threats against our families, especially not on our private phone numbers and alongside disturbing images. We should not normalize abuse like this in sport."

Stefanini lost her Indian Wells qualifying match in three sets.