There's a nagging doubt that accompanies every fighter to the ring as 40 creeps closer—a sinking feeling that the best days may be in the rear view, that enough time may no longer remain to accomplish everything they wanted to in a finite career.
To some, the decay comes early, a product of wear, tear and wars in the ring. Others, like Bernard Hopkins, the former middleweight kingpin who fought until he was 51, can hold Father Time more firmly at bay.
For Gennady Golovkin (38-0-1, 34 knockouts), this doubt sprang distinctly to life in the 10th round of the highest-profile fight of his career—the HBO-televised fight he had spent half a decade building toward and that was supposed to stamp once and for all his first-class ticket into the pantheon of greats.
In the grander scheme of things, what happened in that 10th round in September 2017 was only a little wobble, an awkward sidestep that followed a booming two-punch combination from Saul "Canelo" Alvarez, a Mexican heartthrob who happens to be among the most formidable counterpunchers in the world. It meant next to nothing. Replay showed it was more of a slip than a sign the Kazakh battleship had truly been thrown off course. Golovkin doesn't even rate the incident as something worthy of discussion.
And yet, from that one moment—a mere deviation from what had otherwise been a night of stalking, forward momentum—almost everyone watching could feel uncertainty in their guts.
The controversial result of the bout, a draw most felt Golovkin deserved to win, left no one happy after a fantastic night of boxing. It also added fuel to the flame of speculation that the great GGG would never be able to capitalize on a chance to prove his merit in the ring among peers.
"It was terrible for me," Golovkin told Bleacher Report of the nearly indefensible scorecard turned in by judge Adalaide Byrd. "It was terrible for the fans. Of course it was terrible for the sport. Judges hurt the sport of boxing that day."
But terrible or not, it was reality. For the first time, Golovkin did not have his hand raised after a professional prizefight. For the first time, the master of both the malaprop and the murderous right cross looked, suddenly, startlingly human.
For years, it had been assumed Golovkin would eventually take the mantle of greatness. But even past accomplishments, other victories, came more starkly into focus in the wake of the wobble.
Had he not looked a little off against the bigger, more athletic Danny Jacobs a few months earlier? Why, after 23 consecutive stoppages, had both Jacobs and Canelo been able to leave the ring after 36 minutes of fighting under their own power, seemingly little worse for wear? Was there reason for concern?
Now 36 years old, Golovkin—and his legacy—will face those questions Saturday at T-Mobile Arena in Las Vegas. In his long-awaited rematch against Canelo, Golovkin faces a true opponent that's even more formidable in the ring than he is as a top drawing card.
In what could be a record-breaking 21st consecutive middleweight title defense, he'll battle time and batter away at boxing history, desperate to carve out the kind of legacy that will make him immortal.
"Triple G is going for a record of title defenses," promoter Tom Loeffler says. "Canelo, if he wins, he takes the titles that Gennady worked so hard to get. So both sides have a lot to win. It's very rare when you get two of the top fighters in the sport of boxing and also two of the most marketable fighters in the sport of boxing. That's what really makes, I think, this event such a big event."
The problem with Golovkin's 20 consecutive title defenses has mostly to do with the names on the list. The previous generation's champions, men such as Felix Sturm and Sergio Martinez, departed the sport without meeting Golovkin in the ring. Their successors, Miguel Cotto and later Canelo, seemed just as hesitant before Canelo eventually took on the challenge.
It leaves Golovkin with a match history that is good—his memorable moments stand the test of time, even if many of the soon-to-be-forgotten opponents won't—but not quite good enough to rate when compared to historical greats like Marvin Hagler and contemporary fistic gods like Hopkins.
Boxing historian Patrick Connor, though impressed like most with Golovkin's forward-moving, wrecking-ball style, doesn't believe he's done enough to be considered among the all-time greats.
"His team keeps pointing to him being on the cusp of breaking a middleweight defense record, but in an era with so many title belts, that's the kind of thing that rings hollow unless the opposition was damn good," Connor says. "His hasn't been."
"It hurts his all-time standing, though it won't affect it as much if he manages to defeat Canelo decisively this time. If he doesn't, that's a problem."
"Granted, it's not his fault he was openly avoided by both Sergio Martinez and Miguel Cotto," Connor adds. "But Golovkin has no signature wins—no Felix Trinidad, no Oscar De La Hoya on his resume."
On the phone from his training facility at Big Bear Lake in the mountains of California, the idyllic locale where Abel Sanchez has tried to create an oasis to escape such concerns, Golovkin's trainer just sighs when asked about the results against top opponents. His protege hasn't looked quite as amazing against the best two foes on his long resume. Of course. Who, he asks, does?
In the gym, Sanchez claims to have seen little in the way of decay. While others may doubt, wondering whether a fighter closer to 40 than 30 can still measure up to an in-his-prime, 28-year-old Canelo, Golovkin is as focused and sharp as the day he first walked into the gym, Sanchez says. That was eight years ago now, when the kind of fighter he's only encountered a couple of times in a life spent in boxing ended up on his doorstep.
"You see talent like Gennady's very seldom," he says. "I've come across it twice. First, it was [former world champion] Terry Norris, who was an exceptional athlete but didn't have the punching power that Gennady does. Gennady Golovkin is one of those gifted athletes who God gave the tools to do this kind of thing, and he was lucky enough to find this sport and excel at it."
But even the most partisan of Golovkin supporters admits that, ultimately, Golovkin will be judged by what happens Saturday—his 40th pro fight in some ways every bit as important as the 39 previous bouts combined.
"He's been getting the short end of the stick for a long time, both in Germany [where he fought the majority of his fights from 2006 to 2011] and in the U.S.," Sanchez says. "But he's been a trooper about it. ... He's just gone about his business and fought whomever they put in front of him. He has not had those opportunities, and because he's not getting those opportunities, he did the best he could to create his own drama and demand.
"Since he was avoided for so many years, by so many other good fighters, this fight will represent a microcosm of his career. If he does what we think he can do, what I think he can do, then we'll remember him as this great middleweight. If not, everyone will question him the way they do all fighters and say we were putting him on a pedestal."
"I think the world will look back and say, 'He didn't do it against supposedly great guys when both were at the top of both their levels,'" he adds. "Is it fair that we expect this of him, instead of just being the great middleweight that he is? No. But that's what happens when you're at that level."
The rematch includes a wrinkle that was lacking in the first bout. That was a mere athletic contest—two of the world's top contemporary fighters in a matchup to settle the central question sports can answer: Who's better?
This one has become something more.
First, there was the bitter outcome of the initial bout, a decision Golovkin and his team blame on boxing's ever-present corruption and politics. That changed the equation, removed the smiles that permeated the first fight's promotion. And then there were Canelo's failed drug tests for clenbuterol, which forced the cancelation of a rematch in May and led both sides into spats of increasingly heated rhetoric.
"I know his true face," Golovkin says. "I know who I am, and I know who the real Canelo is. Because he failed the drug tests, I think he is a dirty fighter. The way he handled that situation shows me he has no respect for the sport or the fans."
A few days later, on a media conference call, the normally affable Golovkin went one step further.
"I want to punish him," he says. "For all the bad things him and his team have done."
Of course, meting out that punishment is the entire purpose of this sport—and Canelo was deftly able to avoid it in the previous bout, showing the kind of footwork and pure quickness Golovkin has rarely encountered.
Team Golovkin seemingly expected the bout to echo the press leading up to it, a close counter-slugfest designed to appease fans. Canelo had other plans, moving well throughout, countering fiercely when cornered, consistently escaping Golovkin's traps by exiting to his left, preventing the champion from blocking his path with the threat of his own shockingly powerful left hook.
"I think we're all surprised. We never thought that he could move as well as he did. He moved exceptionally well," Sanchez admits. "We were thinking, We have a throwback here. We have a throwback, back to the days of [Marco Antonio] Barrera, [Erik] Morales, [Manny] Pacquiao, where they were in front of each other and they were hitting each other. We didn't see that.
"And if I want to put some kind of blame on anything, then I want to blame myself, that I didn't anticipate him moving as well as he did or as much as he did. But the second one, I know he can and probably will. It's something we'll have to wrestle with."
While Golovkin concedes Canelo is the most skilled boxer he's faced, he believes he'll be ready this time to further impose his own will on the fight. For his part, Golovkin sees no evidence he has slowed measurably, no reason to doubt success will continue to come his way. Fighters seldom do, especially those who have never tasted defeat.
If there is doubt, it's in boxing as an institution, in the ability to be judged fairly. But fixing the sport of boxing is a problem too big for even the greatest fighter. Instead, he's turned his attention to Canelo, an equation he believes he can solve.
"You learn from a fight how he reacts to getting hit with a punch and how it affects him mentally," Golovkin says. "You can tell by the way he fights, or in Canelo's case, does not fight.
"Yes, he ran [in the first match]. ... I fought to win. Canelo fought to survive. That is not 'Mexican style' fighting. This time Canelo will feel the pressure. I will make a bigger effort to cut off the ring. I know what to do. I learned a lot from the first fight."
And he has a lot to prove in this one.
Jonathan Snowden covers combat sports for Bleacher Report.