The 24-year-old Rennes keeper was stunned by the impact and fell to the ground hitting his head, and was subsequently ruled a no go for the opening Group B clash with Trinidad and Tobago.
“He was hit by a shot in his face,” said Sweden team doctor Anders Vallentin.
“His head hit the ground. He was never unconscious but quite confused and the symptoms persisted for hours.
“It is too early to play against Trinidad and Tobago. It will take around five or six days for him to get back.
“Right now he is completely fine, but yesterday, he was not. We hope we can rehabilitate him during this period. It is probably not too bad. We will see after a few days. I feel it is reasonable to hope he’ll be back for the second game against Paraguay, on Thursday June 15.”
Isaksson’s freak injury leaves the choice of his replacement to two vastly inexperienced goalkeepers as he has been first choice since after the 2002 World Cup finals.
Coach Lars Lagerbäck will have to choose between Viborg’s John Alvbåge or Norwegian outfit Fredrikstad’s Egyptian-born Rami Shabaan, who played three times for Arsenal before being let go after breaking his leg.