Steve Thompson has been sidelined for four to six weeks with a calf tear.
Steve Thompson has become a major doubt for England's autumn internationals after Northampton revealed he would miss the next month of the season.
Thompson tore his calf muscle in the recent Premiership defeat to Gloucester, meaning he is likely to be sidelined for up to six weeks.
Head coach Paul Grayson said: "The initial signs after Saturday's game were that we had lost our entire front row, but hopefully the damage is not too serious to Tom (Smith) and Pat (Barnard).
"The injuries to Steve (Thomspon) and Bruce (Reihana) appear to be serious ones and put the squad under pressure, but they also give a chance for others to step up."
England have a hectic schedule arriving at the start of November, with Tests against South Africa (twice), New Zealand and Australia all on the agenda.
Thompson is likely to be in the middle of his recovery period during that time - throwing serious question marks over his participation.
Bath's Lee Mears is now likely to be handed the England number two shirt.
