Ong shared on social media that he received threatening messages, including implications of violence, following his and partner Teo Ee Yi's first-round elimination at the Indonesia Masters on January 20.

"I will bring a knife and hurt Ee Yi’s hand, making you choose between changing partners or quitting," one of the messages reportedly said, as noted by New Straits Times on January 21.

Ong and Teo were defeated by Taiwan's Lee Jhe-huei and Yang Po-hsuan, marking their third successive first-round departure after early exits at the Malaysia Open and India Open.

Malaysian badminton athlete Ong Yew Sin. Image from Instagram/@badmintonphoto_official

"You are not only unworthy of competing against seeded players; you are not even capable of participating in premier tournaments. You are simply a liability to the team, idiots... When I say something, I mean it, and I will ensure it happens. I will use every means at my disposal to compel you to retire," read the messages Ong disclosed.

Ong expressed that he felt distressed and believed the threats had surpassed acceptable boundaries.

On January 22, Kuala Lumpur police chief Fadil Marsus stated that Ong should report the matter to the police since the messages represented a criminal act.

"Ong Yew Sin must submit a report so that inquiries can be commenced and necessary measures taken.

"This is the duty of the authorities. We have a zero-tolerance policy for any reported offenses and will respond appropriately. If there are criminal activities involved, we will handle them as effectively as we can," he told local news source The Star.

The threats directed at Ong are part of a broader trend of online harassment aimed at Malaysian badminton players, a sport that elicits significant national pride owing to the country’s ongoing achievements on international and Olympic stages.

National player Toh Ee Wei has also voiced her concerns about online harassment following her early eliminations at the India Open and the Malaysia Open, with some remarks targeted at her family.

"For me, I’m fine. But my parents are upset; they raised me until I grew up, which was challenging. When people say such things, it’s really hard to hear," she remarked.

In October 2025, the Badminton Association of Malaysia stated it "strongly denounced such conduct" and urged the public "to share their views with consideration and positivity."