floyd mayweather v manny pacquiao is now just eight days away .
sportsmail 's jeff powell has been counting down the greatest fights .
in the fifth in a series of 12 fights that shaped boxing history , we have muhammad ali v joe frazier , the thrilla in manila .
it was said to have come five years late , much like mayweather v pacquiao .
yet those doubting the two greats in their 30s were spectacularly wrong .