LAS VEGAS — Manny Pacquiao’s legendary run of beating big names started when he stopped Marco Antonio Barrera at Alamodome in San Antonio in 2003.

But it was in 2001 that the little-known assassin from the Sarangani province of the Philippines made his United States debut against Lehlo Ledwaba, stopping the South African for a junior featherweight title on the undercard of an Oscar De La Hoya PPV event at MGM Grand in Las Vegas.

Twenty-four years later, at 46, Pacquiao’s journey comes full circle when he returns to the site where he started making a name for himself against San Antonio’s Mario Barrios (29-2-1, 18 KOs) on July 19 to headline a PBC on Prime Video PPV.

“He's a champion and a tough guy, but I'm used to boxing bigger and taller guys. I love challenges,” Pacquiao told The Ring. “I'll do my best to win by knockout. But we can not underestimate him.”

As the recently minted Hall of Famer Pacquiao (62-8-2, 39 KOs) took a trip down memory lane, he listed his wins against Barrera (twice), Erik Morales (two wins, one loss), Juan Manuel Marquez (two wins, one loss, one draw), Oscar De La Hoya, Miguel Cotto, and Antonio Margarito as the best wins of his career.

“Nobody knew me before the Barrera fight,” said Pacquiao.

Pacquiao, an eight-division world champion, also has wins against Hall of Famers Timothy Bradley (two wins, one loss), Ricky Hatton and Shane Mosley as well as former titleholders Keith Thurman, Adrien Broner, Lucas Matthysse, Jessie Vargas, Chris Algieri and Brandon Rios.

Despite also being involved in boxing’s most lucrative fight of all time against Floyd Mayweather Jr. in 2015, a unanimous decision defeat, Pacquiao, who’s earned more than $550 million in his career, is training like he’s still the impoverished kid who grew up on the streets of the Philippines.

“I feel the same hunger in training, but I feel the adjustment in body recovery,” said Pacquiao. “Sometimes we have to take time to rest and let the body recover after intense training. But the hard work is still there. The discipline is still there.”

Pacquiao, an undersized plus-275 betting underdog, would become the second-oldest champion in boxing history if he were to beat Barrios.

“Remember, in boxing, speed is the key,” said Pacquiao. “If I were slow, I would accept that and give up boxing.”