Ann Limongello/ABC News

Say the name  Joe Frazier and the next thought in the minds of most is Muhammad Ali. The connection is inevitable, and with Frazier gone, it may just be eternal.

For all of Frazier’s successes, the Olympic gold medalist and former heavyweight champion, will likely forever be defined by his relationship with Ali. The two were the greatest heavyweights of their era, and two of the greatest of all time. They fought three times, and two — the so-called “Fight of the Century” at Madison Square Garden in 1971 and “The Thrilla in Manilla” in 1974 — are landmarks in the history of the sport.

“They needed each other. … If you’re going to be great, you need someone to measure yourself against,” said ESPN.com Boxing Writer Dan Rafael. “You can’t have the legend of Ali as it is if there is no Joe Frazier on the other side of the ring from him.”

The fighters were known as much for their verbal jabs outside the ring as for their epic fights within the ropes. Ali taunted and mocked Frazier relentlessly in the buildup to each of  their fights, abuse that Frazier would absorb stoically, until he would finally break.

“Ali is the one who pushed the buttons,” Rafael told ABC News. “He knew he could push Joe’s buttons and … even if Ali was not being serious and just trying to drum up interest in the fight, Joe took it very, very deeply personal. And it’s the type of thing that carried on for decades.”

During a 1974 interview on ABC’s “ Wide World of Sports” an argument between the two erupted into a brawl.

“Clearly Ali is horsing around, drumming up interest in the fight, doing what fighters have to do to sell the event,” Rafael said. ”But Joe, who of course had bitterness towards Ali, you put your hands on him and wrestle him to the ground, of course he’s going to take it serious, because it’s not liked they planned it.”

But if Frazier seemed outmatched in their trade of insults, in the ring it was a different story. They had different styles, and Ali may have been flashier, but the punishment Frazier dished out was so great that after “The Thrilla in Manilla,” Ali said, “That was the closest I’ve come to death”  — and he won the fight.

Despite the trash talk, each man had a tremendous amount of respect for the other — at least as fighters.

“If God ever calls me to a holy war, I want Joe Frazier fighting beside me,” Ali said.