The "Greatest" has a challenge for undefeated champion Floyd Mayweather Jr., as Muhammad Ali is urging the American superstar to finally face Manny Pacquiao. Echoing sentiments of many fight fans, Ali made the call on Twitter after Mayweather kept his record unblemished against Marcos Maidana. Mayweather overcame a stiff challenge from the Argentinian, taking a majority decision to unify two world titles. Before Ali’s tweet, Mayweather said his next fight is still up in the air. -- Mornings @ ANC, May 5, 2014.