LAKE FOREST, Ill. (AP) -- Chicago Bears receiver Brandon Marshall is apologizing for firing back at former NFL star Warren Sapp with some harsh comments -- even though he meant what he said.

He says he's sorry for going public with his feelings and probably should have "kept it private."

Instead, he lashed back at Sapp in an online video Monday for calling him a "retard" in a radio interview. He also posted on Twitter later that day that Sapp apparently challenged him to a fight.

On Thursday, Marshall said he had exchanged emails with Sapp, an NFL Network analyst, before posting the video and that it didn't go well. All that stemmed from an interview with the syndicated "The Dan Patrick Show" in which he ripped Marshall for "talking about Shannon Sharpe."