John Riel Casimero was criticized by most netizens for mocking the health condition of Hall of Fame trainer Freddie Roach.

One of those people who expressed dismay at Casimero's antics was WBC bantamweight champion Nonito Donaire.

The Filipino world champion made a special appearance in the recent YouTube vlog (RichDon TV) where he was asked if he wants to be trained by the 61-year-old Roach.

This is where Casimero started to make fun of Roach's stuttering speech.

“Siyempre gusto ko Pilipino. Hindi kami magkaka-intindihan nun,” he said.

"Tapos yung pagsasalita pa hindi pa gaanong marinig. Rarrrrrrrr. Parang robot,” he added.

The antics did not sit well for most netizens, since he straight up disrespected the legendary trainer. 

Ironically, Casimero trained at the Wild Card gym in Los Angeles while preparing for his last title fight against Guillermo Rigondeaux -- a gym that Roach owns.

It is no secret that Roach has been suffering from Parkinson's Disease, which is why the 38-year old Donaire had to express his disappointment towards Casimero.

"That was sad. Freddie is not only a legendary trainer but also a HUMAN BEING,” said the 'Filipino Flash'

“U don’t make fun of someone like that. Not about health. Especially in this sport, we are in, u don’t know when karma will come back around.”