Andy Ruiz Jr is adamant he won't change himself for anyone - not even Luis Ortiz.

Ruiz Jr produced one of the biggest upsets in boxing history as he destroyed Anthony Joshua in seven rounds in New York in June 2019.

But the Mexican-American underdog was blasted for piling on the pounds when he lost the rematch in Saudi Arabia six months later after ballooning up to 20 stone.

'The Destroyer' returns to the ring next month to face dangerous Cuban veteran Ortiz at the Crypto.com Arena in Los Angeles on September 4.

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And it sounds like he is going back to his usual self having parted ways with his former trainer Eddy Reynoso in favour of his fellow countryman Alfredo Osuna, who will be in the corner for his fight against 'King Kong'.

Ruiz told BoxingScene.com: “We’re here again and I’m thankful for another opportunity.

"We didn’t come here to cherry-pick anybody. We wanted a tough opponent and that’s why we picked Luis Ortiz. He’s strong, he’s awkward, he’s a lefty, but we’ve had a long training camp and we’ll be ready. 

Andy Ruiz Jr celebrates after beating Chris Arreola

“The main thing for me is going to be staying busy. I’m not underestimating Luis Ortiz, because he comes to fight. He wants to be world champion. On September 4, we’ll go toe-to-toe and we’ll see who’s going to win.

“It feels good to have this fight set. We know this isn’t going to be an easy fight. He has a different style than what I’m used to, but we’ve trained really hard at the gym to perfect the craft.

"He’s going to bring it, but we just have to do the best we can to get this victory and go on to win world titles. This is a big fight for me to climb back up the ladder.”

At the weigh-in ahead of his comeback fight against Chris Arreola last year, the 32-year-old had slimmed down rather considerably from the portly figure that faced Joshua three years ago.

But Ruiz has hinted that he will put the pounds back on as he prepares to face Ortiz.

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He added: “I wanted to work with Osuna a long time ago, it just wasn’t the right time then. He’s used to training for lefty fighters. I feel like this is exactly what I needed for this fight. My team is going to bring the best out of me.

“The main focus has just been training my skills. This isn’t a weightlifting contest, so I’ve been getting back to what originally made me a champion. I’m not here to lose weight or look the part, I just want to be the part.

“I’ve been doing this all my life. I’ve been fighting since I was six-years-old, so the muscle memory is there. I needed this long training camp for this type of fight. That’s going to help me get comfortable in this fight.

“I think this is a similar fight for me to the Anthony Joshua fight, it’s just that he’s a lefty. We have a great team and we’re working hard. September 4 is going to be a hell of a fight.”