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 and will be sidelined for six to eight weeks.
Riggott's injury comes just days after manager Gareth Southgate strengthened his central defensive resources by landing Real Madrid star Jonathan Woodgate on a season-long loan deal and Chelsea's Robert Huth in a £6million transfer.
Southgate told the club's website: 'It is a real blow for Chris because it is a big season for him and he would not have wanted it to start in this way.
'He has matured as a player enormously over the last couple of years and it is a shame for him that he should pick up an injury like this at this point.
'But we will get on with it. We have just strengthened the centre of defence, so we are better off than we would have been and as always in these situations, it creates an opportunity for others.'
Riggott, who has started each of Boro's three Premiership games this season, was a fixture in the side alongside Southgate during the last campaign.
Woodgate seems a certain starter for Saturday's trip to Arsenal, and versatile Austria international Emanuel Pogatetz is the most likely man to partner him with specialist left-back Andrew Taylor fit again.
However, Huth is making rapid progress as he recovers from surgery to repair the ankle problem which initially caused his move to the Riverside Stadium to fall through.
Ugo Ehiogu and Matthew Bates are injured, leaving only youngsters Andrew Davies and David Wheater in reserve.