He once was a heavyweight champion, and a great one at that. Ali would say as much after Frazier knocked him down in the 15th round en route to becoming the first man to beat Ali at Madison Square Garden in March 1971.

But he bore the burden of being Ali's foil, and he paid the price. Bitter for years about the taunts his former nemesis once threw his way, Frazier only in recent times came to terms with what happened in the past and said he had forgiven Ali for everything he said.

Frazier, who died Monday night after a brief battle with liver cancer at the age of 67, forever will be linked to Ali. But no one in boxing would ever dream of anointing Ali as "The Greatest" unless he, too, was linked to Smokin' Joe.

"I will always remember Joe with respect and admiration," Ali said in a statement. "My sympathy goes out to his family and loved ones."

They fought three times, twice in the heart of New York City and once in the morning in a steamy arena in the Philippines. They went 41 rounds together, with neither giving an inch and both giving it their all.

In their last fight in Manila in 1975, they traded punches with a fervor that seemed unimaginable among heavyweights. Frazier gave almost as good as he got for 14 rounds, then had to be held back by trainer Eddie Futch as he tried to go out for the final round, unable to see.

"Closest thing to dying that I know of," Ali said afterward.

Ali was as merciless with Frazier out of the ring as he was inside it. He called him a gorilla, and mocked him as an Uncle Tom. But he respected him as a fighter, especially after Frazier won a decision to defend his heavyweight title against the then-unbeaten Ali, in a fight that was so big Frank Sinatra was shooting pictures at ringside and both fighters earned a then-astonishing $2.5 million.

The night at the Garden 40 years ago remained fresh in Frazier's mind as he talked about his life, career and relationship with Ali a few months before he died.

"I can't go nowhere where it's not mentioned," he told The Associated Press. "That was the greatest thing that ever happened in my life."

Bob Arum, who once promoted Ali, said he was saddened by Frazier's passing.

"He was such an inspirational guy. A decent guy. A man of his word," Arum said. "I'm torn up by Joe dying at this relatively young age. I can't say enough about Joe."

Frazier's death was announced in a statement by his family, who asked to be able to grieve privately and said they would announce "our father's homecoming celebration" as soon as possible.

Manny Pacquiao learned of it shortly after he arrived in Las Vegas for his fight Saturday night with Juan Manuel Marquez. Like Frazier in his prime, Pacquiao has a powerful left hook that he has used in his remarkable run to stardom.

"Boxing lost a great champion, and the sport lost a great ambassador," Pacquiao said.

Don King, who promoted the Thrilla in Manila, said in a statement issued Tuesday that Frazier was "the embodiment of what a great heavyweight champion and person should be."

"Not only was he a great fighter but also a great man. He lived as he fought with courage and commitment at a time when African-Americans in all spheres of life were engaged in a struggle for emancipation and respect," King said of Frazier. "Smokin' Joe brought honor, dignity and pride for his people, the AMERICAN people, and brought the nation together as only sports can do."

Though slowed in his later years and his speech slurred by the toll of punches taken in the ring, Frazier still was active on the autograph circuit in the months before he died. In September he went to Las Vegas, where he signed autographs in the lobby of the MGM Grand hotel-casino shortly before Floyd Mayweather Jr.'s fight against Victor Ortiz.

An old friend, Gene Kilroy, visited with him and watched Frazier work the crowd.

"He was so nice to everybody," Kilroy said. "He would say to each of them, 'Joe Frazier, sharp as a razor, what's your name?' "

Frazier was small for a heavyweight, weighing just 205 pounds when he won the title by stopping Jimmy Ellis in the fifth round of their 1970 fight at Madison Square Garden. But he fought every minute of every round going forward behind a vicious left hook, and there were few fighters who could withstand his constant pressure.

Joe Frazier's decision victory over Muhammad Ali in 1971 was the first in a trio of legendary fights. AP Photo

His reign as heavyweight champion lasted only four fights -- including the win over Ali -- before he ran into an even more fearsome slugger than himself. George Foreman responded to Frazier's constant attack by dropping him three times in the first round (the first giving birth to Howard Cosell's iconic "Down goes Frazier!" call) and three more in the second before their 1973 fight in Jamaica was waved to a close and the world had a new heavyweight champion.

"Good night Joe Frazier. I love you dear friend. George Foreman" read Foreman's Twitter page.

"He would not back up from King Kong," Foreman said later Tuesday. "I know, I knocked Joe down six times. When our fight was over, Joe was on his feet looking for me."

Two fights later, Frazier met Ali in a rematch of their first fight, only this time the outcome was different. Ali won a 12-round decision, and later that year stopped Foreman in the Rumble in the Jungle in Zaire.

There had to be a third fight, though, and what a fight it was. With Ali's heavyweight title at stake, the two met in Manila in a bout that long will be seared in boxing history.

Frazier went after Ali round after round, landing his left hook with regularity as he made Ali backpedal around the ring. But Ali responded with left jabs and right hands that found their mark again and again. Even the intense heat inside the arena couldn't stop the two as they fought every minute of every round, with neither willing to concede the other one second of the round.

"They told me Joe Frazier was through," Ali told Frazier at one point during the fight.

"They lied," Frazier said, before hitting Ali with a left hook.

Finally, though, Frazier simply couldn't see and Futch would not let him go out for the 15th round. Ali won the fight while on his stool, exhausted and contemplating himself whether to go on.

It was one of the greatest fights ever, but it took a toll. Frazier would fight only two more times, getting knocked out in a rematch with Foreman eight months later before coming back in 1981 for an ill-advised fight with Jumbo Cummings.

"They should have both retired after the Manila fight," former AP boxing writer Ed Schuyler Jr. said. "They left every bit of talent they had in the ring that day."

"The courage Smokin' Joe showed in The Thrilla in Manila -- answering every Ali onslaught with an equally withering response -- will remain in the hearts and minds of boxing fans around the globe forever," King said of the third fight in the trilogy.

"One cannot underestimate the contribution Smokin' Joe and Ali made to progress and change by creating the space, through their talent, for black men to be seen, visible and relevant. The Thrilla in Manila helped make America better," King said.

Born in Beaufort, S.C., on Jan. 12, 1944, Frazier took up boxing early after watching weekly fights on the black-and-white television on his family's small farm. He was a top amateur for several years, and became the only American fighter to win a gold medal in the 1964 Olympics in Tokyo despite fighting in the final bout with an injured left thumb.