England have been hit by a double injury blow to Wasps players Danny Cipriani and Tom Rees.
Fly-half Cipriani is on crutches after sustaining a small hairline fracture to his right fibula, while flanker Rees has undergone a second shoulder operation in three months.
Cipriani, part of the England Saxons squad this season, could be out for up to six weeks, but Rees - a senior England elite squad member - faces at least four months on the sidelines.
England begin their international season by tackling Australia at Twickenham on November 7. They then face Argentina and New Zealand on the next two Saturdays.
In a statement, Wasps said: "Following extensive consultations between Tom, the medical team at London Wasps, the club's orthopaedic team, and the England medical team, it was decided this week that further surgery was required to give Tom optimal results for recovery.
"Sustaining a tear to the labrum (shoulder), Tom underwent surgery in July, but it was felt that to preserve the longevity of his career an additional surgical procedure was to be undertaken.
"This surgery has been completed this week, and it is likely that he will now be sidelined for at least a four-month period as he works through his rehabilitation.
"Following a contusion to his knee in Wasps' Guinness Premiership clash with Northampton last Sunday, further investigations have shown that Danny has a small hairline fracture in his right fibula head.
"This was a direct result of sustaining a blow during the fixture. Danny has remained on crutches, and will do so until further notice. The club will be working towards a six-week return to play."