A fatigue-related withdrawal is not the same as a muscle problem, joint issue or contact injury. The report says the change was made because of physical wear, which points more toward load management than medical alarm.
For a player like Messi, that is significant:
That does not automatically make the situation risk-free, but it does change the conversation.
At this stage of his career, Messi does not need to prove he can get through every club match at full throttle. The priority before a major tournament is usually rhythm, freshness and availability. A controlled substitution can be part of that process.
There is also a tactical angle. Teams built around Messi need his decision-making and calm in decisive moments more than nonstop running in the days before a global tournament. If the issue is simply accumulated fatigue, the focus shifts from fear to management.
The real clues will come from training intensity, recovery work and whether Messi looks comfortable in the final build-up. One early substitution on its own is less important than the pattern that follows.
The next storyline is straightforward: does Messi train normally and arrive at the World Cup looking sharp? If he does, this may quickly be remembered as a sensible precaution rather than a warning sign.