Floyd Mayweather Jr. smiles Friday during the weigh-in before his fight… (Al Bello / Getty Images )
LAS VEGAS — A boxer needs an edge, contentment is the enemy.
Consider the case of Floyd Mayweather Jr.
The unbeaten world welterweight champion used to argue with any doubters that he was superior to Manny Pacquiao in the debate over who was the best pound-for-pound fighter.
That's no longer an issue after Pacquiao was knocked out by a man Mayweather previously dominated, Juan Manuel Marquez.
Mayweather has also longed to boast about his riches. Then, earlier this year, he signed a 30-month, multi-fight deal with Showtime/CBS that is valued at potentially $200 million, considered the most lucrative deal for any athlete in any sport. His base salary for this fight is $32 million.
But if Mayweather is looking for a new challenge, he can always think of battling father time.
The 36-year-old Mayweather has been out of the ring for a year and during that period spent nearly three months in jail for his conviction in a domestic violence case involving the mother of his three children.
As a result, the idea that Mayweather could slip in his Saturday night title defense against Robert Guerrero is gaining some traction among bettors. Mayweather (43-0, 26 knockouts) is almost a 7-1 favorite, but that is down from 9-1 last month.
Mayweather, before a recent workout at his gym, defended his drive to improve to 44-0.
"You can never be satisfied and let your guard down," he said. "Always try to be better than you were before. Stay focused and continue to work hard.
"I want to put those extra steps in front of me to the Hall of Fame." He added, "I don't overlook no opponent, that's something I don't do."
But what is the significance of Mayweather's change in trainers, booting his longtime cornerman and uncle Roger Mayweather in favor of his father, Floyd Mayweather Sr.?
Mayweather said his father is skilled at teaching defense, and his uncle is suffering vision problems because of diabetes.
"I can't afford for nobody's vision to get bad in a big fight like this," Mayweather said.
The champion also said his jail stay influenced him. "I'm going to grow closer to my family, and do things a lot different. My dad is sick," with the lung disease sarcoidosis, Mayweather said.
"If I never made a bond with my father and something harsh happened, it would hurt me not speaking to him, and it would hurt me for him not to have a relationship with his grandchildren," Mayweather said.
"That's very, very important and I have to be the bigger person, asking my dad, 'Why are me and you arguing, when we are both in this sport to be the best? Why not work together?'"
Although Mayweather won his last fight over Miguel Cotto, Mayweather was marked up by the end of the bout.
So, in training, Mayweather Sr. had his son focus on increasing his head movement, plus a heavy reliance on the jab — which the elder Mayweather says is the key to beating Guerrero.
"These guys in here training with him are 22 … Floyd's damn near 40, and he's not getting hit," Mayweather Sr. said. "Things are getting better. Everybody in here is saying that. I'm getting him back in the groove of things."
Mayweather Jr. said jail taught him, "I'd rather have my freedom and be poor than be rich and not have freedom." Some close to him believe incarceration also brought some clarity about how he wants to leave the sport.
Mayweather is committed to a Sept. 14 date that could be a super-fight against Mexico's star world super-welterweight champion Saul "Canelo" Alvarez.
"I felt like pushing myself, testing my skills against other top fighters. Being 36, I don't have a lot of wear and tear on my body. I still got all my faculties — still sharp, still smart, still witty," Mayweather said. "If I give 'em 30 months, that's enough and I'll go to the other side after six fights."
Understandably, Guerrero sees forces at play that could diminish Mayweather.
"He's trying to set himself up as the best fighter ever, and the pressure is on him to keep his legacy going," Guerrero (31-1-1, 18 knockouts) said. "He's signed this big contract. You have a lot of stuff to fulfill."
Fight promoter Richard Schaefer said Mayweather "needs to deliver" in the face of his climbing age, his television deal, his change in trainers and the jail experience.
"But I do think through jail he realized he's closer to the end than the beginning of his career," Schaefer said.
Before a workout last month, the elder Mayweather summoned his son to his side and kissed him on the forehead — a healing moment after the pair split in a televised, obscenity-laced argument two fights ago.
Mayweather Jr. said, "I love my father. … The main thing is winning. You can never stop learning. I just want to be a winner."