Captain Farrell has been suspended since last month's warm-up victory over Wales and the fly-half watched on from the stands as England beat Argentina and Japan to go top of Pool D at the tournament.
A victory in northern France on Saturday will almost guarantee a quarter-final spot for a side who were heavily criticised before the competition.
"I wouldn't describe myself as a good watcher," Farrell said on Thursday.
"I feel involved, like I'm out there at times, I feel every emotion that goes with it. Sometimes a bit more so than if I was playing."
Farrell takes over the playmaking duties from George Ford who kicked a hat-trick of drop goals in the win over the Pumas.
"Everyone was practising them from halfway after that first game," Farrell jokingly said.
England coach Steve Borthwick has made 12 changes to his team, which include handing Marcus Smith his first start at full-back, against the lowest-ranked side in the World Cup.
"Marcus is a fantastic player," Farrell said.
"Everyone knows what a talent he is. Hopefully we can link up, get each other involved in the game."
Despite the two early successes, England have been slammed for their lack of creativity with ball in hand.
They have also kicked the ball more often than any other outfit in the World Cup.
"I get the passion that the crowd brings, I get the will that they want us to do well," added Farrell who will celebrate his 32nd birthday on Sunday.
"The team has done unbelievably well to find ways to win Test matches, to find ways to close out games, to dominate at times in period," he added.
'Huge respect'
Directly facing Farrell this weekend will be Chile fly-half Rodrigo Fernandez, who scored a superb solo try against the USA during qualifying.
"I think he's a great player," Fernadez said of Farrell.
"He comes back with a lot of desire to play. I have so much respect for him, it's a huge challenge for me to go against him."
Chile head coach Pablo Lemoine, who spent time as a player with Bristol more than 20 years ago, has made nine changes to his team.
He has an eye on the next World Cup having guided Los Condores to their first appearance in the tournament.
Chile have lost twice so far, to Japan and Samoa, having conceded 85 points but they have gained a lot of respect for their attacking mentality.
"We are in a World Cup but we are still working for the next four years," former Uruguay prop Lemoine said.
"We have to give the youngsters some experience at that level.
"We want to give them a chance, and a chance to play against a Tier 1 country."
