Unbeaten Maywether will move to within one win of heavyweight great Rocky Marciano’s famous 49-0 career record if he gets past Pacquiao??next month.
The American says he is ready to call time on his own career later this year after a 49th fight and world titles in five different weight classes.
And Hagler, the Hall of Famer whose career-defining victory against Thomas Hearns came 30 years ago this week, believes fear of losing that unbeaten record is keeping Mayweather going.
“I think Floyd is a person that don’t want to lose,” Hagler told Sky Sports News HQ. “I think he’s going to be relying on his skills and everything to try to maintain that unbeaten streak.
“Marciano was a very tough warror. he didn’t have size but he had power. Floyd Mayweather has another type of gift – he’s able to use his hand speed and he’s very intelligent. That’s something that could work in his advantage.
“He has to continue to win because i don’t know if he can accept defeat.”
Pacquiao has waited five years for a shot at Mayweather after negotiations back then came to nothing, and the Filipino great has lost twice in the interim.
But Hagler said: “A fight like Mayweather can bring best out of Pacquiao. Maybe he’s never fought anything like he’s going to fight with this fight.
“We’ve got to wait and see, because we haven’t seen the teeth of either one of these fighters yet.”