The undefeated Mayweather (43-0, 26 KOs), who has said he has 30 months of boxing left before he brings the curtain down on his career, was a picture of calm as Ruben Guerrero screamed at him: "We are going to beat the woman beater".
Mayweather served two months of a 90-day sentence for domestic violence last year.
"I don't have to sit here and badmouth his father," shrugged Mayweather after the news conference. "Only God can judge me."
The fight in Las Vegas on Saturday will mark a turning point in Mayweather's often contentious relationship with his own father, Floyd Sr, who will be in his corner for the first time since a March 2000 win over Gregorio Vargas.
"My dad is sick, and if I never made a bond with my father and something harsh happened, it would hurt me," said Mayweather of his father, who has been suffering from sarcoidosis. Mending fences with his father, he adds, has yielded professional as well as personal benefits.
"There's certain things only my dad may see in training camp," he said. "For this fight, I made sure I got more rest.
"My dad said, 'You need the rest. And when you've rested, you can come back and box in the gym and you're going to look a lot better.' And he was right. I feel like I'm in tip-top shape, tip-top condition. I'm ready to fight."
Guerrero, too, is ready to fight, and believes Mayweather has invited more stress on himself by starting the countdown clock on his career.
"They say the pressure is on me. The pressure is on him to stay undefeated, to keep his legacy going," Guerrero (31-1-1, 18 KOs) told reporters on Wednesday. "He has these 30 months left, and he's got a lot of stuff to fulfil, so I think the pressure is on him and not me."
Guerrero first called for a fight with Mayweather in 2011, even though at lightweight he was two weight divisions lower.
However, he made the step up to welterweight and scored two victories last year, including a thrilling brawl with former title holder Andre Berto in November, to earn the shot at Mayweather's title.
"Definitely, I absolutely believed I would get (the fight)," said Guerrero. "That's why I kept on it, and kept fighting the fights I needed to get myself in position to make it happen, and here it is."
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