Rival Super Bowl fans will attend the big game together after one donated his kidney to the other

• Rival Super Bowl fans will attend the game together after a kidney donation.
• John Gladwell and Billy Welsh met each other serving in the Marines 20 years ago.

An incredible story featuring military service, a brotherly bond, and a kidney donation will see two fans from rival Super Bowl teams attend Sunday's big NFL game together at State Farm Stadium in Glendale, Arizona.

Meet Kansas City Chiefs fan John Gladwell and Philadelphia Eagles diehard Billy Welsh, who first met one another while serving in the Marine Corps. more than 20 years ago.

Though they lived in two different parts of the country after completing their service, they stayed in touch on social media.

Then, one day, Welsh posted something on Facebook that caught Gladwell's eye in 2019.

"Does anyone have a spare kidney I can get?" Welsh wrote. "Mine are junk."

Gladwell had to check with Welsh that he wasn't kidding, as he had a reputation as a joker.

They relayed their story on the Today show Wednesday.

Welsh had been diagnosed with polycystic kidney disease. According to Mayo Clinic, this is an inherited disorder that sees clusters of cysts develop inside the kidneys and causes the organ to swell and lose function over time.

Welsh needed a donation.

Gladwell, meanwhile, went to find out if he could donate his and discovered he was a perfect match. Soon after, he told his old friend of the news, and they underwent a 10-hour surgery in Philadelphia.

'You don't leave someone behind'

"You never leave your brother behind," said Gladwell. "Marines are a band of brothers. You don't … don't leave someone behind."

He added: "I wasn't going to let his son grow up without his dad being there for everything."

Said Welsh: "It's a whole new lease on life … I was worried if I didn't get a kidney, my son would grow up without a father."

As news of Gladwell and Welsh's story circulated around the football community, the presidents of the Eagles and the Chiefs got together and found a way to get the guys to the Super Bowl.

"The opportunity to bring these two guys together, their two teams playing on the biggest stage in sports, it's very, very humbling and gratifying," Don Smolenski, Eagles president, told The Philadelphia Inquirer.

"[With] a Chiefs kidney … I don't know how my body will react if the Chiefs win," Welsh said on the Today show. "The Eagles are going to win. Go birds!"

Watch their story here: