Cuba's boxers have been the poster-boys of its amateur sports ethos for over five decades.
Drilled to fight for the country, not for cash, they have won an impressive 34 Olympic gold medals over the years.
But in a move that would have been unimaginable while Fidel Castro was in charge, the island's elite fighters are now entering the ring as professionals for the first time.
Ten top Cuban boxers have been sent to Mexico for their first foray into the World Series of Boxing this week. Run by the governing body of amateur boxing, AIBA, the league allows fighters to receive a regular salary as well as bonuses.
Cuba's communist authorities are currently considering going even further, allowing boxers to join a fully-professional series with 10-round fights that AIBA plans to launch next year.
Boxers in both series remain eligible for the Olympics.
So at La Finca training camp on the edge of Havana, the workouts have been even more rigorous in recent months.
By 07:30 each morning, two dozen or so elite fighters have been breaking a sweat in the cavernous, well-worn gym, sprinting, skipping and shadow-punching to the commands of their exacting coach.
They have had to up their game for the World Series, where they face five-round bouts instead of the three they are used to as amateurs.
They will also shed their protective headgear and shirts.
"We know it's different. But nothing is impossible," defending World Champion bantamweight Lazaro Alvarez shrugged, a few days before departing for the exhibition match in Mexico.
Cuban fighters routinely go eight or 10 rounds in training, he pointed out, and he had no worries about losing the head guard.
"You have to be more careful, more defensive, to make sure the blows don't go straight for your head. But you readjust," he said.
The World Series was launched in 2010 and AIBA has been courting participation by Cuba - a nation that has produced boxing legends like Teofilo Stevenson and Felix Savon, with three Olympic triumphs apiece.
"This event will lift the athletes' level a lot and so lift the quality of boxing at the Olympics. It is precisely what we needed to stimulate our athletes," believes national coach Roland Acebel, who sees the new style as more dynamic.
"We have a slogan that a boxer is made by fighting. If he doesn't fight, he falls behind," he argues, adding that his team is filled with new enthusiasm.
But there are other factors driving this radical shift in policy. Like many Cuban sports, boxing has been badly hit by defections in recent years.
Fighters can earn as little as the $20 (£13) average monthly state salary and even champions take home under $300 a month.
In the run-up to the 2008 Beijing Olympics, several boxers skipped the country to try their fortune in the professional ring, and Cuba failed to win gold for the first time since 1972.
Anxious to retain the rest, trainers talk of increasing the "psychological" work with fighters; the Boxing Federation says it helped resolve complaints over perks such as apartments and cars - and Cuba signed-up for the World Series.
An official at the state sports institute, INDER, told the BBC that boxers' salaries will vary between $1,500 and $5,000 a month plus bonuses.
If so, that would be a huge increase - although an undisclosed cut will be retained by the state.
"I'm mainly surprised this change took so long," says John Duncan, author of In the Red Corner, an insider's account of Cuban boxing.
The sport has been amateur-only on the communist-run island since 1961.
John Duncan believes Cuba's reticence stemmed from its "strong distaste" for professional boxing, rooted in the exploitation of Cuban boxers by US promoters before the revolution.
"Now it seems that Cuba's decided that if its boxers are going to defect and go pro and there is money to be made, then the state should get a piece of it," the writer argues, pointing out that the athletes pay nothing for their years of training.
"Sport is everywhere in Cuba, it's an integral part of the system. But it's expensive to keep all that going now there's less money," he adds.
So if it ever turns a profit, the World Series could help plug the funding shortfall.
"We will improve conditions for our athletes. We will improve the quality of their training, and their quality of life," National Boxing Federation chief Alberto Puig concedes of the new venture.
But he insists that Cuban boxing retains a higher calling.
"The fundamental motivation for the fighters, is demonstrating what Cuban boxing is capable of," Mr Puig argues. Some argue that the true test of that would be in the fully professional ring.
Cuba says joining the AIBA professional series is "an option" that it is studying. AIBA says it "would be delighted" to welcome them, in the future.
But for now the fighters' own ambitions remain unchanged.
"For me, to be an Olympic champion would be the highest achievement," says Julio Cesar la Cruz, a light heavyweight who missed out on a medal last year in London.
In the future, he could achieve that as a professional.