Former USC running back Anthony Brown used Instagram on Thursday to call head coach Steve Sarkisian a racist. Brown had quit the team last week.

"Sark treated me like a slave in his Office ... Can't play for a racist Man!!! #Fighton," Brown said on Instagram. He also posted a similar message on Facebook, according to ESPN.com.

Post posts were quickly deleted.

Sarkisian immediately rejected Brown's characterization of him, when it was brought to his attention.

"As far as what [Brown] said on Twitter, it's ridiculous," Sarkisian said. "Any of you guys who know me and if you ask anybody in our building, any of our players -- feel free to -- that's about the furthest thing from the truth. Quite honestly, I'm shocked."

Brown, a former cornerback, requested the move running back and was sixth on the team's depth chart at that position. But his opportunity to move up the depth chart was limited due to a hyperextended elbow.

Sarkisian, however, said Brown was expected to play a key role on the team this season once he fully recovered.

"Anthony decided not to play football anymore," Sarkisian said. "We obviously tried to encourage him not to quit. We thought he could be an asset to our team, especially when healthy. We really tried to make it a point to accommodate the position change he wanted. He wanted to move to running back and we did so.

"He unfortunately got injured in training camp and was working his way back and decided he didn't want to play anymore. It's a bit unfortunate because we could have used him. We think he could have helped us."

The reaction on Twitter to Brown's comment was swift, with an overwhelming majority of respondents denouncing Brown and coming Sarkisian's defense.

Brown's comments come on the heels of fellow-USC football player Josh Shaw being suspended from the team indefinitely for fabricated that he suffered anke injuries while attempting to pull his nephew from a pool.