Tony Adams and Steve McManaman will almost certainly miss England's next Euro 2000 match against Germany in Charleroi on Saturday.
Both men suffered injuries in last night's 3-2 defeat by Portugal.
McManaman limped off after suffering a knee injury while attempting to make a tackle in midfield, while centre-half Adams' notoriously fragile back appeared to give way as England attempted to chase the game.
England coach Kevin Keegan said: "They have both gone for a scan but the feeling is that Tony will not make the next two games and Steve will not be fit for the match against Germany."
Asked to assess England's performance, Keegan added: "I can certainly think of a fair few things we could have done better but there were a lot of plusses in there that get overlooked.
"Our finishing was good and our character was good. I'm disappointed but I still feel we've got it in our own hands.
"Yes, it's more difficult now. We probably have to win both games."