Football can be a precarious career. There are no guarantees. Momentum can be derailed by so many events: an unwise move, a change of coach, pure bad luck. But there is nothing worse than the dreaded injury, especially to the knees.
This is a panful subject for a pair of Brazilians who broke through together and whose current teams faced each other this week in the Copa Libertadores.
Centre-back Dede and central midfielder Romulo made their names in the Vasco da Gama team that won the Brazilian Cup in 2011 and came within a whisker of eliminating eventual champion Corinthians in the following year's Libertadores.
A giant figure, Dede was also gifted with pace. Indeed, he was something of a late developer because his speed was liable to take him out of position. Once he sorted out that problem, he was a towering influence on the game, cleaning up in the air in both penalty areas and sufficiently quick to cover the entire defensive line.
In front of him, Romulo was a quiet match-winner. Such was his speed and anticipation that he rarely had to make a tackle. He was consistently getting to the ball first and his distribution was crisp and slick. Vasco were very strong down the right flank -- where attacking full-back Fagner, who featured in the recent World Cup, made his mark.
But it was Romulo who was winning the ball in the centre and passing quickly out to the flank. He looked to have something of Clodoaldo, the central midfielder of Brazil's wonderful 1970 side, in him. Both Dede and Romulo seemed destined for long international careers.
Vasco had overreached themselves in the quest for trophies and needed to sell players to balance the books. On the verge of the 2012 Olympics, Romulo signed for Spartak Moscow in Russia. Had he waited then, he would have had options in the Premier League. His performances on English soil during the warm-up games and the Olympics alerted local clubs to his potential. But the Spartak deal had already been done. Romulo hit the ground running in Russia -- but soon he suffered a serious knee injury, and was out of action for over a year.
By this time Dede, too, was about to run into problems. He could have gone to Europe but was one of the few Brazilian players not to have this as an ambition. He elected to stay in Brazil. With Vasco desperate for funds, he was sold to Cruzeiro in 2013. The following year he smashed his knee, setting off a period of some three-and-a-half years in which he barely played a game. He went through unsuccessful surgeries, followed by problems with his other knee, and endured spells when it was doubtful if he would ever play again. He was unable to make a consistent comeback until earlier this year.
By this time, Romulo was back in Brazil, picked up by Vasco's old rivals Flamengo. He was their great midfield hope for 2017 but it was immediately obvious that he simply was not the same player. He looked heavier and much, much slower. Gone was the player who appeared to glide across the field. Instead, he looked distinctly ordinary.
At the start, there was a hope that this was just teething troubles but that hope has since been extinguished. It has become increasingly apparent that the Romulo of 2011-12 no longer exists. Romulo is not 28 until next month, but he looks worryingly like a spent force. He was not in consideration even for a place on the bench on Wednesday night when his Flamengo hosted Dede's Cruzeiro in the second round of the Libertadores.
The Dede story, though, is much more uplifting. He may not be quite as quick as before but his positioning is sound and he has been in fine form. He came close to a place in Brazil's World Cup squad. And with a little more time, he may have won the fourth center-back slot. He is certainly in contention for a recall now, with the Russia 2018 combination of Miranda and Thiago Silva both well into their 30s.
Having Just turned 30, Dede still has some time left -- and he pushed his claims with a magnificent performance in the Maracana, holding Flamengo at bay and providing the platform for Cruzeiro's 2-0 win.
Romulo could be forgiven for watching the match with a bitter taste in his mouth. Not only because he was not selected and his team lost, but also because, if it was not for that knee injury, this is the type of occasion that may have given him the opportunity to shine. Instead, he is one more perambulating on the boulevard of "what ifs."