Stipe Miocic and Derrick Lewis ... get ready -- 'cause Greg Hardy says he's coming!!!
"They're not in my mind," the ex-NFL star says of the UFC heavyweight beasts ... "They're in my sights, brother. They're locked in."
Of course, Hardy ain't sure exactly when those fights will go down ... he tells TMZ Sports, after being DQ'd in his first-ever UFC fight -- he's got a lot to learn before he steps in the Octagon with the superstars.