Farrell started at inside centre then switched to fly half when George Ford (30) was taken off early in the second half but was far from his best, as were most of his team in an error-strewn display that needed Danny Care's (36) late try to scrape an 18-17 win.
Borthwick now needs to decide whether to continue on Sunday with the Ford-Farrell 10/12 axis which was so good at the last World Cup but was in action for the first time since the 2012 Six Nations against the Samoans.
If he feels it is not the answer for Fiji, the question is whether to revert to Ford at 10, the set-up for the first two games where he produced man of the match performances while Farrell was suspended, or drop him and start Farrell in his preferred position.
Borthwick has stood four-square behind Farrell since the day he got the job and, though he dropped him to the bench for the 2021 France Six Nations game to give Marcus Smith an opportunity, he soon had him back on board as first choice 10.
On Saturday, in recognition of Farrell overtaking Jonny Wilkinson to become England's leading points scorer, Borthwick said: "It's testament to a man who's dedicated himself to being the best he can be, the best player he can be, the best leader he can be, the best person around the squad.
"I think he's an incredible role model. It's a privilege for me as a coach to be able to work with him and hopefully there'll be many more times in that England shirt and (he'll) continue to play as well as he does."
It hardly sounded like a prelude to a benching and Borthwick is not the sort of coach to make radical changes for the biggest game of his short England tenure.
Asked about the prospect of starting with Marcus Smith (24) after he came on at full back and injected some pace and posed Samoa some new questions, Borthwick said: "We're trying to expedite things very fast here... there are some combinations we haven't been able to run very much recently. We are learning from every minute of every game and every minute of training because that's what we need to do."
Borthwick probably feels the best way to beat Fiji is through the sort of aggressive, tactical strangulation England applied in their impressive opening win against Argentina.
They are certainly not going to try to take the Fijians on in an 80-minute game of Sevens the way Portugal did.
England never looked like scoring a try versus Argentina and would be quite happy for a repeat if they can tick the scoreboard over with penalties.
Ford ran the show superbly against the Pumas and chipped in with three key drop goals but Farrell is also adept at shifting his team around the pitch via tactical kicking and moving him to fly half enables Borthwick to beef up his midfield defence.
Borthwick, like Eddie Jones and Stuart Lancaster before him, wants his "standard setter" on the pitch whenever and wherever possible. "The big players perform on the big stages," he said. "And they're all looking forward to next Sunday in Marseille."
