Rio Ferdinand has told Michael Stewart to "educate" himself as he took exception to the pundit's comments about Glen Kamara.
The Rangers midfielder has made an allegation of racist abuse against Ondrej Kudela of Slavia Prague, and UEFA have opened an investigation.
The centre-back was seen whispering in Kamara's ear with his mouth covered by his hand.
The Rangers star says he was called a "f*****g monkey" and that team-mate Bongani Zungu heard it, with the club and manager Steven Gerrard offering their full backing.
Kudela and Slavia deny any wrongdoing, but some felt Stewart went too far in pointing that out, accusing him of casting doubt on Kamara.
The pundit compared the incident to a previous one against Ross County, and told fellow guest Richard Foster that people "could make anything up" if society jumps to conclusions.
While Stewart was clear that he would unequivocally condemn any racist abuse, his cautious stance proved controversial.
And fomer England international Rio Ferdinand has now weighed in, writing on Twitter: "Educate yourself @mstewart_23... comments like this are why people suffer in silence & are scared to speak out!"
The Man United legend's brother had also criticised Stewart, urging the pundit to his his platform to pressure UEFA into action.
He wrote: "Your comments can make the victim feel not believable! How about you use ur platform to call for UEFA to make sure a proper investigation takes place & when found guilty, the correct punishment happens.
"For too long it’s brushed under the carpet!"
The former St Mirren centre-back was involved in a high-profile incident in which it was alleged that John Terry had racially insulted him on the pitch.
The Chelsea man was acquitted by a criminal court as the claim could not be proved beyond a reasonable doubt, but copped a four match ban from the FA.
