Miguel Diaz has been the cutman for 36 world champions, including Manny Pacquiao and Floyd Mayweather Jnr. He's trained nine fighters to world titles and is considered one of the sport's most articulate and knowledgeable figures.
It will be another day at the office for the 76-year-old Argentinian-born American when he works in the corner of Hong Kong's Rex Tso Sing-yu, who returns to the ring on Saturday night's "Champions of Gold" bill in Macau.
Tso received a big boost when he received confirmation the Hall of Fame trainer will work his magic again after the Hong Kong fighter was knocked down twice before winning by unanimous decision in May's "Featherweight Fury" showpiece.
Tso suffered a broken blood vessel in his nose and severely bruised hands before finally dominating Thailand's Ratchasak Kokietgym.
"I owe Miguel a lot from that fight. Miguel is a real lifesaver. I don't know what would have happened if he hadn't helped us that night," said Tso (13-0-0, 8 KOs), who takes on Indonesia's John Bajawa in a six-round, non-title bantamweight fight at the CotaiArena.
Tso weighed in at 117.5 pounds, exactly the same as his opponent.
Diaz said he was pleased his skills were appreciated and agreed to work in Tso's camp because he's a "likeable guy".
"Rex has a big future," said Diaz, who trained Erik Morales, the first Mexican to win world titles in four weight divisions. "He is a young fighter and has to learn the trade. He has such a big heart and he shows it in the ring.
"He showed a lot of character in his last fight. It was very tough for him, but he responded really well.
"If I had to give him a rating right now, I would give him 6.5 to seven out of 10. He's a good fighter," said Diaz of the 27-year-old.
"Give him another five or six fights and I think he can become world champion."
Although Diaz has a fine record as a trainer, he's probably known as the world's best cutman, having worked in Pacquiao and Mayweather's corner, among many others, including China's two-time gold medallist Zou Shiming.
"I was Mayweather's cutman for his first 17 fights," said Diaz proudly. "I was there from his very first pro fight. I even trained his father [Floyd Snr] and his uncles Roger and Jeff. Yes, four Mayweathers."
Meanwhile, an ornate custom-made belt specially designed for Zou will be in his possession if he wins tonight's main event.
"I want this belt, it's beautiful," said China's two-time Olympic gold medallist after organisers revealed the World Boxing Organisation (WBO) special elite international flyweight belt that will be put on the line.
"It's the first time I am going for a title since I turned professional more than a year ago. It's a milestone for me and I am confident I have the ability to claim this belt," said the Guizhou native, who will be looking for his fifth straight professional win.
The belt is only sanctioned for bouts that feature a fighter of elite stature. Past recipients of this honour include Filipino superstar Manny Pacquiao and Mexico's Juan Manuel Marquez.
Zou (4-0, 1 KO) will first have to defeat Colombia's Luis de la Rosa (23-3, 13 KOs) before he can take home the belt.
Zou weighed in at 111.5 pounds, while De la Rosa was 110.5 pounds.
Another bout tonight features two-time Cuban Olympic gold medallist Guillermo "El Chacal" Rigondeaux (13-0, 8 KOs) against Thai veteran Sod Looknongyangtoy (63-2-1, 27 KOs) for the WBA/WBA super bantamweight title.