One of the more memorable greetings that Brazil's Ronaldo received from an opponent during his storied career was "Next time, I'll break your teeth," delivered by Roberto Ayala, the Argentine, during an infamous Milan derby one October night in 1999.
Ayala, then of AC Milan, never had the chance to play orthodontist. Ronaldo, then playing for Inter Milan, was sent off for what he described as a protective elbow raised against his persecutor. Ayala received a red card later on.
Nearly a dozen years after that incident, Ronaldo has had something else broken. Not his teeth, not cartilage, tendon or his weakened knee, but a part of his being that cannot be healed, or temporarily patched up.
His enthusiasm for playing a game he once mastered better than any of his contemporaries has been sapped to the point he could take no more. He chose St Valentine's Day to announce he had fallen out of love with being a professional footballer.
One of the most remarkable aspects of Ronaldo's career, which he brought to a close by telling a press conference he had cancelled his contract with Corinthians after being jeered and abused by fans, was its longevity.
Defenders in the Dutch Eredivisie, in Serie A, in the Primera Liga and in Brazil have been trying to break Ronaldo, who turns 35 in September, for nearly two decades.
After each of the several points when a hard, gruelling sport seemed to have cracked him for ever, he kept coming back.
He would be robbed of much of his sleek mobility very young, after arriving in Serie A, but still he recovered to look like the most effective goalscorer anywhere while at Real Madrid.
It was a month after Ayala had threatened him that Ronaldo felt an excruciating pain in his knee in a match for Inter against Lecce. He had been with the Italian club for just over a season, following a then world-record transfer - the fee was worth around US$30 million (Dh110.1m) - from Barcelona. He had already won the Ballon d'Or, aged only 21, and twice been named Fifa World Player of the Year.
But Ronaldo was under physical strain, as he developed his upper body strength and because, with his speed and close control, opponents would act desperately to impede him.
As early as 1996, Bobby Robson, the then head coach of Barcelona, told me: "He's ahead of anything I've ever seen for his age. But he gets hit by defenders, so I hope it can last."
Before Ronaldo was 24, it looked as if it would not. His comeback from the operation on his knee lasted seven minutes, in the Coppa Italia final of 2000 against Lazio.
Two further stints in surgery followed, so the lead-up to the 2002 World Cup became a saga of touch-and-go whether Ronaldo would make it. His 1998 tournament - when he suffered mysterious convulsions on the day of the final against France, was left out of the starting XI and then reinstated very late on before Brazil's 3-0 loss to the hosts - had been disappointing.
But World Cup 2002 would be Ronaldo's finest hour. He scored both goals in the final against Germany, his seventh and eighth in the tournament.
That helped earned his transfer to Real, and the scorn of Inter: "He's ungrateful" said Massimo Moratti, the president of the club who had weathered his bad injuries for four years.
At times at Real, his work-rate would be questioned, his weight would rise, but he was also a devastating striker. He also won his first European league medal, the Primera Liga title in 2003, having won only cups with Barcelona and Inter.
He helped Real towards another league in 2007, but by then his dynamism was fading. A brief stint with AC Milan had only occasional cameos, but reminders that at his peak, Ronaldo had been a marvel, 'Il Fenomeno', a phenomenon.