It was civil rights campaigner and feminist author Rita Mae Brown — not the frequently credited Albert Einstein — who defined insanity as “doing the same thing over and over again and expecting different results.” And while at least a light splash of insanity is almost a prerequisite for deciding to become a boxer, it is indeed rarely advisable for a fighter who has already lost once to a particular opponent to box that opponent again the exact same way he did the first time and expect to have his hand raised in the rematch.

Nevertheless, many boxers do just that. They convince themselves they just had an off-night, or they can win just by being in a little better shape, or they just got caught with one lucky punch, or the judges are to blame, and on and on. Sometimes there’s truth to that. But often, adjustments — whether minor or major — must be made to reverse a result when opponents clash a second time.

As we roll into the first weekend in December, rematches to close and/or thrilling fights appear to be in vogue. This Saturday in Phoenix, we get two on one card: Emanuel Navarrete-Oscar Valdez II and Rafael Espinoza-Robeisy Ramirez II. On Dec. 21, it’s the big one: Oleksandr Usyk-Tyson Fury II for the heavyweight championship of the world. New Year’s Eve brings us Fernando Martinez-Kazuto Ioka II in Tokyo. The co-feature on the February 1 Prime Video Pay-Per-View is the arguably overdue Stephen Fulton-Brandon Figueroa II. And atop the February 22 Riyadh card that the boxing world is buzzing about, it’s Artur Beterbiev-Dmitry Bivol II for the undisputed title at 175 pounds.

Several of those first go-rounds were damned close, and Bivol and Figueroa in particular could reasonably believe they deserved to win. But for the most part, those who suffered defeats the first time will need to make some sort of tactical tweaks to flip the script — as many of boxing’s finest fighters of the past did in what turned out to be some of the most glorious wins of their careers.

Probably the greatest and most high-profile example ever of a successful strategy shift came in a fight known best for the two words the loser said at the conclusion. The “no mas” fight was a black mark on Roberto Duran’s legacy, but that shouldn’t obscure the heaps of credit Sugar Ray Leonard deserves for pulling a complete tactical 180 from their first bout and convincing Duran to utter those two words.

Famously, Leonard fought Duran’s fight the first time around — he wanted to prove he was man enough to rumble with “Hands of Stone,” so, rumble he did, losing a close unanimous decision at Olympic Stadium in Montreal on June 20, 1980. In the rematch five months later, Leonard fought the exact opposite of Duran’s fight. He never stopped moving, always punching while in motion, just looking to score points rather than do physical damage, and Duran had no answers.

Trainer, historian, and Boxing Scene contributor Stephen “Breadman” Edwards showed his super middleweight contender Caleb Plant that very performance last year heading into his bout with David Benavidez.

“I showed him how Leonard would punch on the move, make Duran reach, tie him up, and rinse and repeat,” Edwards said. “With Leonard being longer, bigger, and faster, it was really, really tough for Duran to overcome that, because Leonard was an elite amateur, probably the best amateur in the history of our country at his weight class. It was an excellent, excellent game plan and adjustment — and it was a fight that, if Leonard loses it, that’s his second loss in a row, his career is totally derailed. He had everything to lose, and he fought a brilliant fight.”

Edwards also pointed out that despite losing the first fight, Leonard finished strong. So it gave Sugar Ray a huge mental edge in the rematch to start fast. “When he gets off to a really good start, and Duran knows what kind of fighter he is down the stretch and how good his endurance and stamina is, it was demoralizing,” Breadman analyzed. “Duran’s saying to himself, ‘Man, this guy closed like a savage on me in the last fight, and now he’s out to this big lead? I’m in trouble. There’s no way I’m gonna pull this fight out down the stretch with the way this man finished in the first fight.’”

As fight fans still struggle to fully understand Duran’s surrender 44 years later, that’s one more strong piece of logic to explain why the Panamanian great quit in the eighth round.

Leonard-Duran II is perhaps the most extreme and most high-profile example of a skilled boxer leaning all the way into his skills to reverse a defeat, but it’s far from the only example.

Five years ago, as was the case with Duran, many focused on the loser of the rematch and his questionable conditioning when Andy Ruiz failed to repeat his shock knockout of Anthony Joshua. But it would be improper to overlook what a disciplined technical exhibition “AJ” put on to even the score by near-shutout decision. “I just wanted to put on a great boxing master class and also show the sweet science of this lovely sport,” Joshua said afterward. “It's about hitting and not getting hit.”

Similar analysis would apply to Leo Santa Cruz’s 2017 revenge win over featherweight titlist Carl Frampton six months after their first fight. In their initial meeting, Santa Cruz slugged it out for 12 rounds and came up just short on the scorecards, so in the rematch, he vowed to use his height and reach advantages and box more and he did just that, reducing his overall output but pumping out persistent jabs to score a deserved majority decision.

It would be a stretch to say Evander Holyfield completely reinvented his fighting style for his 1993 rematch with Riddick Bowe. But, under the tutelage of Emanuel Steward, Holyfield brawled less than he did the first time and constantly broke Bowe’s rhythm with jabs to the chest, jabs to the head, and counter double jabs. The fight is largely remembered for the “Fan Man” interruption, but Holyfield did a fair amount of interrupting of his own to turn a unanimous decision loss the first time into a majority decision victory in the rematch.

Arturo Gatti was famous for giving into the temptation to go to war despite his appreciable boxing skills, but on rare occasions, he listened to his corner’s advice. Perhaps his most disciplined effort was his 2002 rematch with Micky Ward, six months after their all-time classic that underdog Ward won by majority decision. Gatti boxed for (at least parts of) all 10 rounds, and even used this thing called defense to make Ward miss periodically, plus when he knocked Ward down in the third round, Gatti didn’t quite go all-out to finish him. His reward was a lopsided unanimous decision in a fight nowhere near as memorable as their first — but far better for Gatti’s health, record, and career longevity.

But perhaps the best example post-Leonard-Duran of putting the Leonard approach to work came from one of Sugar Ray’s last conquerors: Terry Norris. In December 1993, the chinny Norris suffered a major upset, by fourth-round KO, at the hands of Simon Brown. When they did it again five months later on the Don King mega-card known as “Revenge: The Rematches,” Norris served the dish that is revenge with his feet as much as his fists, winning a wide unanimous decision. “He outmoved me and he outboxed me,” Brown acknowledged afterward. “He moved a lot. I expected that, but he just wouldn’t stand still at all.”

There are plenty of other cases that in various ways echo the Leonard approach — Chiquita Gonzalez outpointing Michael Carbajal after getting KO’d in their thrilling first fight, Sergey Kovalev decisioning Eleider Alvarez to avenge an upset defeat that appeared perhaps career-ending in the moment, etc. — but sometimes revenge can be earned with the exact opposite type of adjustment.

Sometimes, a fighter has to make the decision to be more authoritative the second time around, and bully his opponent in a way he failed to the first time.

Two fairly recent examples require a slight asterisk because they were rematches to draws, not losses, but both Saul “Canelo” Alvarez and Tyson Fury clearly know a thing or two about stepping forward when the 13th round begins.

Against Gennady Golovkin, Alvarez allowed himself to be backed to the ropes repeatedly in their first fight, and many considered him lucky to escape with a draw. He stepped right to “GGG” in their second battle and, despite a late-round fade, won a less controversial decision.

Tyson Fury avenged his draw against Deontay Wilder much more emphatically, doing precisely what he promised he would do (even though nobody believed him). Fury attacked the most dangerous puncher in the heavyweight division, gave him no room to breathe, importantly gave him no room to wind up and punch, and put a beating on him until the towel came in midway through the seventh round.

As Breadman Edwards pointed out, “Everybody since that fight has fought Wilder the same exact way that Fury did. Wilder has taken three bad losses since the second Fury fight because Fury set the blueprint on how to fight him.”

There are also plenty of cases in boxing history in which a loss was reversed through aggression in which it happened so quickly that it’s hard to know whether to chalk it up to a strategy shift. Still, Joe Louis-Max Schmeling II, Roy Jones-Montell Griffin II, Ryota Murata-Rob Brant II, and Paul Williams-Carlos Quintana II are among the most impressive revenge victories ever scored, and certainly some sort of tactical adjustment was made in each of these blowouts.

And then there’s one all-time magnificent rematch adjustment that fits neither the “more technical boxing” category nor the “more aggressive punching” category. It features a man who, perhaps by the time you read this, will officially be an International Boxing Hall of Fame inductee.

In his first fight against Erik Morales, in March 2005, Manny Pacquiao was still a somewhat one-dimensional, one-fisted fighter, and he came up two points short on each scorecard after 12 rounds. In the 10 months that followed, leading up to their rematch, Pacquiao and trainer Freddie Roach worked hard to develop a southpaw right hook, and they devised a game plan that included quite a few right hooks to the body. Morales got off to a decent start, but by the middle rounds, the new Pacquiao was wearing him down, and he dropped Morales twice in round 10 for a rematch revenge stoppage.

Even though Edwards has never personally trained a fighter for a major rematch to a tough loss, he can speak to the idea of training someone to box in a style that isn’t entirely natural to them.

“I had Kyrone Davis just beat Elijah Garcia, and he used a counterpunching style and just landed right hands, and when he fought Anthony Dirrell, he used a bounce-in-and-out Holyfield kind of style — and neither one of them is his natural style,” Breadman said. “And Caleb Plant just fought Trevor McCumby on the inside, after I told him, ‘Hey, man, you gotta turn into a savage, don’t give him any room.’

“It’s just a matter of your instincts letting you know what you think the guy can do, from watching them in the gym. Just because a person is not known for doing something, that doesn’t mean he can’t do it.”

Starting this Saturday and in the weeks ahead, we’ll learn whether Oscar Valdez, Robeisy Ramirez, Tyson Fury, Kazuto Ioka, Brandon Figueroa, or Dmitry Bivol are capable of doing something they didn’t do the first time around.

All six of them are crazy enough to trade punches for a living. Whether any of them fit the informal definition of insanity will be known soon.

Eric Raskin is a veteran boxing journalist with more than 25 years of experience covering the sport for such outlets as BoxingScene, ESPN, Grantland, Playboy, Ringside Seat, and The Ring (where he served as managing editor for seven years). He also co-hosted The HBO Boxing Podcast, Showtime Boxing with Raskin & Mulvaney, The Interim Champion Boxing Podcast with Raskin & Mulvaney, and Ring Theory. He has won three first-place writing awards from the BWAA, for his work with The Ring, Grantland, and HBO. Outside boxing, he is the senior editor of and the author of 2014’s . He can be reached on or , or via email at RaskinBoxing@yahoo.com.