Andy Ruiz Jr. has a message for those who question his Mexican roots and cast doubt over his claim to being the country's first heavyweight world titleholder.

"Everyone who thinks I'm not Mexican simply because I was born in the United States is wrong," Ruiz told ESPN. "I represented Mexico trying to go to the Olympics. I'm always fighting for the Imperial Valley [in Southern California where he lives] and Mexicali, Baja California, Mexico. In my pro and amateur fights I've always mentioned Mexico. My mom and dad are from Mexicali, and I feel more Mexican than others who were born in Mexico because I fought for my race and for Mexico."

Ruiz knocked out Anthony Joshua in the seventh round last Saturday to win the WBA, IBF and WBO titles at Madison Square Garden in New York.

Ruiz said his historic accomplishment hasn't yet sunk in. He will travel back to Mexico next week to meet Mexican President Andres Manuel Lopez Obrador.

"It's something incredible," Ruiz said. "I'm pinching myself to see if this is real, but I feel very proud to have won the titles and made history. It's a goal I've had since I turned pro.

"I'm nervous, I'm happy, I'm all over the place as if I were dreaming, and very proud and happy that I'm meeting the president."

Ruiz said his life has been turned upside down since knocking out Joshua.

"People tell me that I've also changed their lives making history," he said. "I'm just coming from the fight and haven't even had a chance to go home to be with my kids. They still have me here [in Los Angeles]."

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His only concern for the moment is spending time with his five children -- Bella, Andy III, William, Richie and Beverly -- before traveling to meet Lopez Obrador.

"I want to enjoy it and hug my little ones," he said.

Underdog fighters will now certainly look to Ruiz for inspiration, but he said he was only focused on the task at hand against Joshua.

"I didn't think about that, you know," Ruiz said about not being favored. "The only thing I wanted was to be Mexico's first heavyweight champion and to beat that big guy that everybody was scared of. Thank God we did it. I beat him, not by decision but by knockout, and I feel so grateful to God that he helped me out."

Ruiz, who will be a candidate for Mexico's Premio Nacional de Deportes (a distinction of merit for athletes who excel in their sport) through the country's boxing federation, will meet Lopez Obrador at the invitation of national boxing commissioner Miguel Torruco.