Ray Hatton believes size could be the decisive factor when Oscar de la Hoya and Manny Pacquiao fight at welterweight in Las Vegas on Saturday.
De la Hoya, 35, is the naturally bigger man, having fought as high as middleweight, whereas Pacquiao, 29, is moving up from lightweight.
Hatton told BBC Radio Merseyside: "I think Oscar is too big for Manny.
"If all things are equal, it comes down to the old cliché of a 'good big one will beat a good little one'."
Hatton, who manages his son Ricky's career, will be ringside for the fight at the MGM Grand at the weekend.
Both de la Hoya and Pacquiao have been touted as future opponents for Hatton, possibly in a marquee fight next summer.
Given Ray Hatton's thoughts regarding Oscar's size, he feels that Pacquiao is arguably a more suitable opponent for his son.
"Obviously if you're looking at it size-wise there's very little difference between Richard and Manny Pacquiao," he said.
"Manny will have this fight at 147 pounds [welterweight] and he's very, very comfortable, by all accounts, at 140 [light-welterweight - Hatton's natural weight].
"He feels more comfortable, I believe, at 140 then he does at 135 [lightweight]."
Ricky Hatton has previously said he would fight either man, preferably at Wembley.
"Let's hope my next opponent is the winner of Pacquiao-de la Hoya," he said in the aftermath of his victory over Paulie Malignaggi last month.
"Who am I to say who will win that? In fact, the winner or the loser will be a good fight, to be honest."
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