Striker Dimitar Berbatov will miss Manchester United's Premier League match at Aston Villa on Saturday after suffering a thigh injury, his agent said.
"According to Manchester United's medical staff Berbatov will be recovering between seven and ten days," Emil Danchev told Bulgarian Darik radio.
Berbatov was substituted after 30 minutes with cramp during Bulgaria's 6-1 defeat against their Balkan neighbours Serbia in a friendly on Wednesday.
United manager Alex Ferguson is also sweating on the fitness of Rio Ferdinand and Wayne Rooney, who missed England's 2-1 win over Germany through injury and illness.