Frank Gore, owner of the third-most rushing yards in NFL history, makes his pro boxing debut Saturday night against former NBA player Deron Williams. While training for the bout, Gore found an unlikely sparring partner and supporter, who also happens to be well-versed in his gridiron glory – Chad Johnson.

"What Frank will do Saturday isn’t surprising to me because I’ve seen it for years, said Johnson via NFL.com. "But he’s going to surprise the world."

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SANTA CLARA, CA - DECEMBER 28:  Frank Gore #21 of the San Francisco 49ers runs with the ball against the Arizona Cardinals at Levi's Stadium on December 28, 2014 in Santa Clara, California.

SANTA CLARA, CA - DECEMBER 28:  Frank Gore #21 of the San Francisco 49ers runs with the ball against the Arizona Cardinals at Levi's Stadium on December 28, 2014 in Santa Clara, California. (Ezra Shaw/Getty Images)

Johnson, who fought a four-round exhibition over the summer and is planning a second fight next year, sparred with Gore earlier this month and came away impressed, and sore.

"That shit hurt. The punches f—ing hurt. He’s heavy-handed," Johnson NFL.com’s Cameron Wolfe. "He’s out of my weight class, but I tried to sit in the pocket, giving him a look for what Deron could present. I caught one of the left hooks. It hurt. I was like, nah, let me get outside."

TAMPA, FLORIDA - DECEMBER 17: Deron Williams and Frank Gore pose during a weigh in at the Hard Rock Hotel and Casino ahead of this weekends fight on December 17, 2021 in Tampa, Florida.

TAMPA, FLORIDA - DECEMBER 17: Deron Williams and Frank Gore pose during a weigh in at the Hard Rock Hotel and Casino ahead of this weekends fight on December 17, 2021 in Tampa, Florida. (Mike Ehrmann/Getty Images)

Exchanging punches with Johnson should help Gore adjust to the height of Saturday’s opponent, Williams. The five-time NBA All-Star is 6’3, Johnson is 6’1 and Gore is generously listed at 5’9. "We’re putting the work in and looking good in the ring," added Johnson.

The bout between Williams and Gore is the first professional fight for either athlete. They’ll enter the ring as part of the undercard to Saturday’s main event, the Jake Paul – Tyron Woodley rematch.

"I’m nervous every day. Even when I just think about it. Just because I want to do good," said Gore. "If I’m being real, my whole 16-year career in football, I was nervous. When you have success, it’s hard to keep having success."

TAMPA, FLORIDA - DECEMBER 17: Frank Gore poses during a weigh in at the Hard Rock Hotel and Casino ahead of this weekends fight on December 17, 2021 in Tampa, Florida.

TAMPA, FLORIDA - DECEMBER 17: Frank Gore poses during a weigh in at the Hard Rock Hotel and Casino ahead of this weekends fight on December 17, 2021 in Tampa, Florida. (Mike Ehrmann/Getty Images)

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Gore hasn’t made any predictions for how the fight will pan out, but he does want those in attendance and those viewing from home to walk away with one shared thought: "After the fight, I want people to say, ‘This man is different."

Chad Johnson can attest.