Gudmundsson will instead stay at the team hotel in Frisco, Texas. The nature of the illness has not been confirmed, but the wing-back is not required to isolate from the rest of the squad, and press officer Petra Thoren clarified that the "symptoms are mild".
Still, it is far from good news for Blagult - Gudmundsson is an expected starter for Graham Potter's side, the news comes less than a week before Sweden's first game of the 2026 World Cup, against Tunisia on 15th June in Monterrey, Mexico.
There is cause for optimisim elsewhere within the team, as the other 25 members of the squad will participate in the session, a few days on from their final warm-up match against Greece which featured several nervy moments for the home side.
Benjamin Nygren and Anthony Elanga both suffered knocks, while captain Victor Lindelof didn't play despite prior suggestions that he would feature. But after touching down in Dallas, Potter was happy with the state of his squad.
"Everyone has made good progress. There are flaws. They have responded very well so I expect everyone to be in training later this week."