The uncapped Northampton star will now mount a credible challenge to senior duo Marcus Smith and George Ford, as England gear up to start their Six Nations training camp.
Head coach Borthwick branded Fin Smith’s half-back pairing with Alex Mitchell at Saints as having developed “beyond any expectation” this season.
Mitchell and Fin Smith piloted 14-man Northampton’s gritty 26-23 Champions Cup win at Munster on Saturday, in a timely confluence of the poetic and prosaic sides of his game.
England must do without former captain, talisman and record points-scorer Owen Farrell for the Six Nations, after the 32-year-old took a Test match break.
Even without the 112-cap stalwart fly-half though, Borthwick was bullish enough about his outside-half options to find himself purring away.
And Northampton 21-year-old Smith’s form appears a significant reason why.
“The partnership that Alex Mitchell and Fin Smith have developed this season has accelerated I think beyond any expectation from where it was, on their ability to handle those key pressure moments,” said Borthwick, at Monday's Six Nations Launch in Dublin.
“Because in all games there are key pressure points, and in that game there were a lot of key pressure points. And they handled them brilliantly.”
Marcus Smith has been in prime form for Harlequins, with the men from The Stoop sitting second behind Northampton in the Gallagher Premiership table.
Quins have secured a home draw in the Champions Cup last 16 with Smith to the fore in European action too, balancing offensive cunning and necessary pragmatism to fine effect.
Sale’s seasoned campaigner Ford still ranks as one of England’s most influential players, helping to shape the Red Rose side’s attacking blueprint.
"I think most coaches around the world would love to be in the position I’m in"
England will open their Six Nations account by taking on Italy in Rome on February 3 – with Borthwick admitting he has a big call to make at No 10.
“It’s a great position to be in, I think most coaches around the world would love to be in the position I’m in,” said Borthwick.
“We've got three incredible players there, all playing very, very well. I think it gives some tactical flexibility in terms of how I want to play, and I think that it’s an exciting position to be in.
“I’ve met with all three of those guys in the last couple of weeks, and all three of them can’t wait to get going.
“That decision’s got to be made there for the Italy game. Would you want that kind of decision to have to be made in every position? Absolutely. I think we’re spoiled for choice there.”