Serena Williams is praising Meghan Markle for her interview with Oprah ... saying MM showed strength and bravery by calling out "malicious, unfounded gossip and tabloid journalism."
Williams -- just hours after Markle's stunning revelations about the Royal Family aired Sunday night -- issued a lengthy statement on social media applauding her good friend for the talk.
"I know first hand the sexism and racism institutions and the media use to vilify women and people of color to minimize us, to break us down and demonize us," the tennis superstar said.