Manny "Pac-Man" Pacquiao's November clash with Brandon Rios in Macao could be his last if he fails to get past the US fighter.

Contacted soon after the Nov 24 date for the fight at the Venetian Macao casino was announced, the Filipino's long-time trainer, Freddie Roach, said it was a case of win or retire for arguably the greatest fighter Asia has produced.

Pulling no punches when contacted by ESPN, Roach said, "If he loses I will tell him to retire.