And potential England honours are also on hold, with Farrell being ruled out of head coach Andy Robinson's autumn Test plans.
The 30-year-old former Great Britain rugby league captain has undergone toe surgery to rectify a problem which surfaced during an innocuous pre-season training match with his new club Saracens, and the Premiership outfit do not expect him to regain full fitness for eight weeks.
Farrell has already sat out three league games and could miss another five Premiership matches, in addition to two Powergen Cup fixtures and Saracens' European Cup appointments with Biarritz and Treviso.
Saracens had intended introducing Farrell in a friendly against Bedford last month, but those hopes were dashed and he then underwent scans to try and identify the injury's exact nature.
It was not until exploratory surgery on Wednesday that the problem was revealed as deep bone bruising.
"We are obviously disappointed that Andy has been ruled out for a further period of time," said Saracens head coach Mike Ford.
"But now he's had the surgery we are pleased that the healing process has begun and we look forward to welcoming him back on the pitch."
Farrell joined Saracens earlier this year in a deal jointly funded by the club and the Rugby Football Union, suggesting he would be fast-tracked into England contention heading towards their 2007 World Cup defence.
But England boss Robinson must now shelve any short-term plans regarding Farrell. He is due to name a 30-man autumn Test squad next Tuesday.
"I've had frequent updates on Andy's injury and the England and Saracens medical teams have been in regular contact," said Robinson.
"Like everyone connected with with his club and England, I would like to wish him a full and speedy recovery."
Farrell arrived in union as one of the league code's most decorated players. He won Super League and Challenge Cup honours with Wigan, and captained Great Britain at the age of 21.
Earlier this year he received an OBE for services to the sport before switching codes and setting his sights on further success, but injury means those ambitions remain on hold.