The legend of Pacquiao continues against a dangerous, younger Thurman

Cheryl Diaz Meyer for ESPN

Boxing careers are built upon the ruins of faded heroes. It's a rite of passage in which the remains of the past are fed to the young. Usually, these affairs are foregone conclusions, more a blood-smeared graduation ceremony than a fight. But not always.

Athletes strive to cheat time the same way we all try to outrun the Reaper. Nobody wins in the end and we know it, but it doesn't stop us from leading fate on a merry chase. It's one of mankind's few redeeming attributes.

Saturday's match between undefeated welterweight titleholder Keith "One Time" Thurman and aging Filipino legend Manny Pacquiao promises more than just a symbolic ass-kicking.

It is not likely to be Rocky Marciano knocking Joe Louis through the ropes or Lennox Lewis hammering the last vestige of fight out of Mike Tyson.

Pacquiao, the designated geezer in this bout, appears to have considerably more fight left in him than Louis and Tyson did. He's been milking the long goodbye for all it's worth, which in his case amounts to tens of millions of dollars.

The truth is, Manny is in too deep to quit now. He's still a bankable commodity and fully intends to run out the string until it snaps like a frayed bungee cord.

Pacquiao's waning years have been marked by a gradual modification of his former Death Star offense. Less is more when you've had 70 bouts since turning pro in 1995.

These days the fight plan is get in, get off and get out. Pacquiao will open up if he thinks his opponent is hurt, but he understands he can no longer get away with fighting like a grenade-spitting whirligig. Well, not too often, anyway.

Thurman, 30, has been talking like never before, excitedly responding to questions with idiosyncratic riffs and animated body language. It has provided considerable internet mirth.

It's been difficult at times to understand exactly what Keith is on about, but the gist is that he's got Pacquiao right where he wants him -- ready to be crushed like an empty peanut shell on a barroom floor.

And why shouldn't Thurman feel that way? He's 10 years younger, bigger, fresher and favored by many pundits. He's feeling it. He knows Saturday could change his life.

But Pacquiao doesn't care about that.

He's a different kind of fighter, a mercenary who enjoys his work and still believes in himself. Those are unquantifiable factors but factors all the same. At age 40, Manny readily accepted the Thurman fight. That should tell us something.

Pacquiao (61-7-2, 39 KOs) is a first-ballot Hall of Famer regardless of what happens Saturday at the MGM Grand Garden Arena in Las Vegas. But he's still a long way from Canastota, and needs regular cash infusions in order to keep his many business interests liquid and to continue living like a king. The glory is nice, but Manny's in it for the money.

Apparently in a bid to buy some extra motivation, Thurman told TMZ he will bet $10,000 on himself knocking Pacquiao out in the first two rounds.

"I can't go three minutes going 'tap tap tap' when I got $10k on the round," Thurman told TMZ. "You know what I mean? I gotta swing a few times. You gotta try to hit a home run."

He's right. A long fly ball caught on the warning track won't do.

Thurman opened as a modest -150 favorite to win, but the line has turned as the fight draws near (Pacquiao -145/Thurman +125, according to Caesars Sportsbook on July 13). There are a number of reasons for this, including Pacquiao's name recognition. Manny is a brand. Keith is just another boxer, albeit a very good one.

A decisive victory over Pacquiao would enhance Thurman's Q rating, and if it's by knockout, he'll be on the "Jimmy Kimmel Live!" show playing his flute the next week.

But what about Pacquiao?

If he wins, Manny will be so hot he might even persuade Floyd Mayweather to come out of retirement. If not, there are smaller but still massive paydays waiting for him, matches that would likely provide a helluva lot more entertainment than another waltz with Mayweather.

Even if he loses to Thurman, Manny will keep going back to the well until the bottom falls out of the bucket. It's the only thing he can do.

The elephant in the ring will be Thurman's lengthy layoff. Hand and shoulder injuries, plus subsequent surgeries and rehabs, kept him out of the ring from March 2017 to January 2019, when he returned with a majority-decision win over Josesito Lopez.

Lopez, known as the "Riverside Rocky," hurt Thurman in the seventh round with a left hook and straight right, and he did enough overall to earn a generous 113-113 draw on one official's scorecard. The right guy got the decision. It's just that he didn't look particularly good doing it.

Thurman's supporters were quick to point out it was a gutsy move to take on a tough, come-to-win veteran after such a protracted layoff. Besides, overcoming a rough patch is something good fighters do.

Valid points, but if the same Thurman who struggled with Lopez shows up Saturday, he can kiss his 10 grand and undefeated record goodbye.

Nevertheless, despite his existential, counterculture vibe, Thurman can fight. He beat highly regarded contemporaries Shawn Porter and Danny Garcia to get to this point. But nobody's quite like Pacman. His mystique has worn thin, but he retains the embers of greatness.

The scary knockout loss to Juan Manuel Marquez in 2012 didn't stop Pacquiao's career, and neither did the embarrassing Floyd Mayweather charade.

Pacquiao abides, an unflappable presence in a perilous business, living on the edge with a serene indifference that serves him well.

"One thing I've learned about Manny Pacquiao along the way is that he knows that being knocked out is part of life and part of the sport," Manny's longtime trainer, Freddie Roach, told Robert Morales of the Los Angeles Daily News. "He understands it, and he accepts it. He accepts losing better than any fighter I've ever seen."

That might sounds like a backhanded compliment, but it's not. If you're going to keep fighting after a bad loss, emotional resiliency is essential.

It's a mindset, along with his diminished but still formidable fighting skills, that has helped Pacquiao stay relevant a decade past his prime.

Pacquiao looked quite good in his two most recent fights, a knockout of Lucas Matthysse and a wide decision over Adrien Broner. Even so, his victims' careers weren't exactly on the upswing. Matthysse has never been the same since getting knocked out by Viktor Postol, and Broner seems to have become comfortable losing and then insisting he won.

Thurman is clearly the best fighter Pacquiao has faced since losing to Mayweather in 2015 and beating Tim Bradley in 2016. It's a legitimately appealing fight, a fading superstar versus a wannabe hoping to use him as a springboard to the elite level.

It's one of boxing's seminal storylines, a generational rivalry with an unspoken subtext -- the old must eventually give way to the new. Exactly when it happens, however, is an open question.

Thurman and Pacquiao will engage in boxing's version of the eternal struggle -- mankind's race against the Reaper -- on Saturday, and there is reasonable expectation they will do it justice.