The former Great Britain rugby league captain has been in this position a number of times before in the 18 months since completing his cross-code switch from Wigan, only for injury to strike him down.
But the difference this time is that Farrell now finally has some competitive rugby union under his belt.
He completed an hour at blind-side flanker for the Saracens second XV in Monday night's Guinness A League game against Harlequins - and impressed boss Alan Gaffney.
"I was delighted what happened. I thought he read the game particularly well. He will definitely be challenging for the bench - there is no doubt about that," said Gaffney.
It was Farrell's first competitive game of rugby in either code since November 2004 - when he captained Great Britain against Australia in the Tri-Nations final.
Farrell missed all of last season after undergoing surgery on a toe injury, and then a prolapsed disc suffered in a car accident.
He has been included in England's elite squad for this season - but after playing his first 60 minutes of rugby union, Farrell had no time for thoughts of Test rugby or the World Cup.
"I'll probably wake up in the morning and feel like I've been in another car crash," said Farrell, who scored the first of Saracens' two tries in a 30-12 defeat.
"But it was good to get out there and feel some contact. It's nice to say I've got the first game out of the way.
"Now I can start ironing out the mistakes I made and concentrate on my rugby instead of worrying about my body."
Farrell's Saracens team-mates have talked enthusiastically about the impact he made behind the scenes during his time on the sidelines - and England coach Andy Robinson hopes to tap into that experience.
He was not captain against Harlequins last night, but it was his voice that could be heard the loudest as he barked instructions and encouragement.
When Saracens fell 12-0 down it was Farrell who delivered the team-talk under the posts - and within minutes of the restart, he had exchanged passes with hooker Matt Cairns down the left wing to score his first rugby union try.
"He is a natural leader," said Gaffney.
Farrell has been working closely with World Cup winner Richard Hill as he attempts to master the demands of blind-side flanker - a position that does not exist in rugby league.
England's watching forwards coach Mike Ford was pleased with Farrell's contribution.
"He got into a few rucks; he scored a good try - and I heard his voice all the way through," said the former Saracens head coach.