Logan Paul has blamed his lacklustre performance in his first fight with KSI on supplement he took before the first bell.
The YouTube stars fought to a draw last year in a white-collar bout in Manchester with Paul struggling with his fitness in the latter rounds.
The pair will bid to settle their beef in Los Angeles on Saturday when they clash in their eagerly-awaited rematch.
And Paul is confident he will not struggle this time after revealing he took a supplement before walking out in the UK.
"I did a lot of things wrong last year but I took a pre-workout before the fight," he told Seconds Out . "I had adrenaline, the crowd, my first time boxing, 15,000 people watching... it was a lot. I can handle a lot... but that was a lot.
"I went from 100-0; normally it's like, 'That round was hard, I'm beginning to feel tired', but at the end of round two I was like, 'I'm a f****** animal!' and at the start of round three I couldn't feel my arms.
"It was a crash and that's not normal, there was no gradual decline. This fight is going to be different, ivwe been sparring 10 rounds every day.
"[KSI's] game plan to rely on me getting tired, which is what he seems to be planning to do, will be a slap in the face when he realises it's not working."
Paul has been training with former heavyweight world champion Shannon Briggs for the sequel after both he and KSI turned professional.
They were granted licences by the California State Athletic Commission and will headline the Staples Center card which features world champions Billy Joe Saunders and Devin Haney.
And Briggs claimed Paul will go on to fight as many as 20 times in the next two years.
"He has amazing reflexes, he's athletic in every way, he has a great jab," he told Sky Sports.
"I think we're looking at the future of boxing, I mean that. I believe he has everything it takes. I believe in time, three to five years, we can be in contention for a real title shot.
"This is not the end, it's only the beginning. He'll be right back fighting very soon. We look to hopefully get 10 to 12 fights next year, and 12 fights the following year."
