 Riggott signed a new four-year deal at Boro in July |
Middlesbrough defender Chris Riggott has been ruled out for up to eight weeks with ankle ligament damage. The 25-year-old suffered the injury in a training ground accident.
Boro boss Gareth Southgate told his club's website: "It is a real blow for Chris. It is a big season for him and he would not want to start it this way.
"But we will get on with it. We've just strengthened central defence so we are better off than we would have been - it creates an opportunity for others."
Boro signed defenders Jonathan Woodgate and Robert Huth before last week's transfer deadline.