Celtic handed fresh concern as summer signing falls ill on international duty

Nygren is understood to be one of three players suffering from illness in the Swedish camp, alongside former Celtic defender Gustaf Lagerbielke and Brighton midfielder Yasin Ayari.

It comes just days after Nygren scored for his country in Monday night’s 3-1 victory over Poland, providing a positive moment away from Glasgow during the international break.

However, Fotbollskanalen report that all three players are now suffering from cold symptoms and will not take part in Thursday’s training session.

Swedish FA press officer Petra Thoren reportedly explained: “Cold symptoms. They are being kept isolated so that we can keep this down to as few numbers as possible.”

It remains unclear whether Nygren will be able to travel with the squad for Friday’s Nations League meeting with Bosnia-Herzegovina.

Sweden have responded to the illness problems by adding St Pauli midfielder Eric Smith to Graham Potter’s squad.

The Swedish FA confirmed: “Eric Smith will join the men’s Nations League squad on Wednesday evening due to an additional case of illness in the squad.

“The men’s national team continues its preparation for the Nations League with training on Wednesday afternoon and Thursday morning. On Thursday afternoon, the team travels to Bosnia-Herzegovina for Friday’s match.

“Given the uncertainty surrounding illness in the group, head coach Graham Potter chose to call up Eric Smith, St Pauli, on Wednesday. Eric Smith was part of this summer’s World Cup squad.”