Brazil's plans for the 2014 World Cup have been fairly stable since their Confederations Cup success last summer. However, since that victory, a number of senior players have been drafted in to take up squad places ahead of a competition that will be a test of mental stamina, as well as ability.
Among those players—a list that also includes the likes of Ramires, Robinho, Willian and Maicon—is Lucas Leiva, Liverpool's long-serving defensive midfielder who has sadly missed so much of recent seasons through injury.
Lucas, while not everyone would agree that his club form had merited inclusion, is a vastly experienced player who is one of the few high-level backup options Luiz Felipe Scolari has available in the anchor midfield role.
Fernando, Shakhtar's talented 21-year-old, attended the Confederations Cup but looks unlikely to be included next summer. Sandro has had injury problems of his own, while Fernando of Porto has been consistently overlooked.
The news this week that Lucas has, potentially, suffered another serious knee injury, as detailed by Goal.com's Peter Marshall, is a blow to those plans. While the midfielder's diagnosis is not yet clear, the player's past record will have Scolari anxiously awaiting news.
Scolari is not without options, but he will have planned for Lucas' presence. Sandro, the most obvious replacement, has also been sidelined in recent times, while other options remain largely untested.
Logic, meanwhile, would see Manchester City's Fernandinho come into contention. The box-to-box midfielder has played a much more defensive role at his new side and has been doing so with aplomb.
However, in Brazil, he is not regarded as a holding player. Scolari may have been tracking his progress in England, but there would be many doubts as to his suitability for such a role at a major tournament.
The hope will be within the Brazil camp, then, that Lucas returns in time for the competition. However, the Liverpool man has plenty to prove in terms of both form and fitness if he is to hold off his rivals.
If he does return, coasting through games, as he has in recent weeks, will convince nobody that he is ready to play at a World Cup. Fernandinho, then, could well find himself included anyway.
The City man will now likely be given the chance to impress in March's friendly encounter with South Africa, when Scolari will have the opportunity to see his talents in person.
Regardless of the outcome of Lucas' injury diagnosis, it may well be that it is his compatriots performance on that occasion that decides his World Cup fate.
Scolari will have been forced to rethink by the events of recent days, but it may be a turn of fortune that actually improves Brazil's squad as a whole. For Lucas, though, it is yet another painful and unfortunate setback.