WHO'S THE GREATEST?

STING LIKE . . . A BUTTERFLY?

Will Smith, who's starring as Muhammad Ali in the new biopic, just can't get out of character -- he keeps bouncing around the house sparring while his kids yell: "YOU'RE THE GREATEST!" But wife Jada Pinkett knows how to keep her heavyweight on the ropes . . . every night before bed she leads Will to a plaque on the wall and makes him read the inscription: "My WIFE Is the Greatest!"