Sport claiming he is out for 15 days.
How do they know ? They haven't even landed yet .
They have doctors and physios with their team.
They check the injury right away and give more or less 90% correct estimation about the injury.
When they come to Barca, they make further tests and scans in the hospital.
Sometimes they later figure out that the injury is in fact more serious, which they couldn't see right after the match without scans.
But in most of the cases, they can estimate the seriousness of injuries right away.