His biggest call was bringing in Marcus Smith (24) at full back, and though his skipping runs rarely broke the Fijian line and he was sometimes gobbled up, his very presence and willingness to take the ball on meant the defence needed to focus on his threat, giving time and space elsewhere.
Some questioned Smith's physicality too in comparison with the giant Freddie Steward (22), but Smith showed again that he is a hugely brave and technically efficient tackler as he went into battle again and again, finishing bloody and battered after suffering a sickening head collision early in the game.
"I thought he defended with a huge amount of courage," Borthwick said. "Not many people talk about Marcus' defence but I thought his defence was very, very good."
Borthwick's other big decision was to drop George Ford (31) and move Owen Farrell (32) back to fly half, and he was rewarded by one of his captain's best international performances for years.
Farrell has always been better at 10 than 12 and he revelled in being the main decision-maker and passed with more sharpness and ambition than at any time during the tournament.
And when it came to his kicking, he made the difference. He landed five of his six penalty attempts, some of them quite testing, one conversion and the key late drop goal that restored England's lead after Fiji had levelled the match with two tries in four minutes.
From the day he got the job, Borthwick has had only the highest of praise for the man he immediately installed as captain and was at it again after the match.
"I think he is a fantastic leader, the kind of leader I know I would want to follow onto the pitch," he said. "I think he is a brilliant player who thrives in the contest and especially in these big occasions he just gets even better. We are very fortunate to have Owen as a player in this team and as our leader."
Removing the Ford-Farrell axis enabled Borthwick to pick two specialist centres and that paid off too as Manu Tuilagi (32) and Joe Marchant (27) each scored a try – a rare centre double for England – and tackled relentlessly to keep Fiji at bay.
The presence of Ben Earl (25) at Number Eight was a foregone conclusion given his form through the tournament, but it should be remembered that it was Borthwick who brought him in from the cold after Eddie Jones had inexplicably frozen out last year's Premiership player of the season.
Asked in the press conference if he felt his selections had been vindicated, Borthwick dismissed the idea, but with a sting in the tail.
"I don't really care what other people think of us, I care about the development of the team," he said. "I said this is a team and squad packed full of talented players who perform on the big occasion and they have performed on the big occasion.
"I think many people wrote we wouldn't get out of the group, maybe some of them are here tonight. The team performed very, very well to top the group and then played well to find a way to win."
