The Edinburgh player is 25 caps into his career but will start a Test match at 10 for the first time in what is a bold gambit from head coach Gregor Townsend.
Kinghorn’s previous international outings have all come on the wing or at full-back but Townsend and his club coach Mike Blair see the player, for the moment at least, as a fly-half.
At 24, Kinghorn is young enough to readapt to the position he played at school but his international opportunities are likely to be curbed by the return of Finn Russell and Adam Hastings.
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Both miss the Tongan game due to club commitments, with Townsend unable to call upon England and France-based players because the fixture falls outside the designated international window.
It means the match-day squad is entirely home-based. There are nine Glasgow Warriors players and six from Edinburgh in the starting line-up, with each club supplying two debutants in the XV and a further two each on the bench.
There will be first caps for Glasgow outside centre Sione Tuipulotu and winger Rufus McLean and Edinburgh loosehead Pierre Schoeman and lock Jamie Hodgson, who will all start at Murrayfield.
It’s the same forwards/backs split on the bench, with the uncapped quartet comprising Glasgow stand-off Ross Thompson and scrum-half Jamie Dobie, and Edinburgh lock Marshall Sykes and back-rower Luke Crosbie.
Scotland will have co-captains for the first time, with Jamie Ritchie and Ali Price sharing the honour.
Thompson is likely to replace Kinghorn at some point but Townsend sees the latter as a serious option at stand-off after being particularly impressed by his performance in Edinburgh’s win over Scarlets in the opening game of the season when he linked the play well and scored a fine try after exchanging passes with the unfortunately injured Mark Bennett.
“I certainly see him as 10 with lots of potential,” Townsend said of Kinghorn. “I’ve seen that in his training sessions, and the Scarlets game. He had some great touches, lovely movement for his try. He put Mark Bennett through a space and then got the ball back himself.
“Game management in attack and knowing when to take on the defence was very good. The kicking side, we know he’s got that ability. But putting that into playing 10 will take some time. Defensively too. We know he’s one of our best defenders on the wing given his pace, the size he is and his reads. But we know it’ll take a little while to get used to defending at first receiver.”
Townsend said the decision to move Kinghorn was driven by Blair who was set to play him at 10 while in interim charge of the national side for the A international against England in June.
Blair’s move to Edinburgh saw the experiment continue but a quad injury has limited the player to just two competitive starts this season.
“I think Mike has been a big driver of it,” said Townsend. “He spoke to Blair about it and Blair has really risen to the challenge of having to lead an attack. He feels it’s a real positive whether he ends up there for the long-term or not because he is much more engaged.”
With the wing berths filled by McLean and Kyle Steyn, Darcy Graham also finds himself in a new position, with the Edinburgh flyer picked at full-back by Scotland for the first time.
“We were really keen to see those three players in the back three involved and looked at different ways we could do that,” explained Townsend. “We know Darcy’s played a bit at full back for Edinburgh and that helped for selection, and it helps his development, playing full-back and reading the game from there.”
McLean runs Graham close in terms of pace and his inclusion makes him the first player born in 2000 to represent Scotland.
“Rufus makes things happen,” said Townsend. “He’s got real acceleration and evasion. But what we’re really impressed with is his work off the ball, his kick chase is outstanding.
“He’s not had many opportunities to win the ball in the air but there was a game last year where he won three re-starts in a row. And also his contact work is very good as is his work rate that you really require at Test level.”
Inside him will be Tuipulotu, an equally exciting inclusion. It will be a particularly notable occasion for the Aussie-born outside centre who has a Tongan father and Scottish grandmother.
“Sione’s a very creative player who likes to get others into the game and he’s also got his own power and acceleration that can get us over the gain line,” said Townsend. “He can be a real connector between the midfield and the back three.”
Schoeman’s fine start to the season with Edinburgh is rewarded with a first start after the South African fulfilled the three-year residency requirement. The prop described it as an “absolute dream come true”.
Behind him will be Hodgson who is partnered with the experienced Rob Harley in the second row. “We love Jamie’s attitude of getting up and knocking people down,” said Townsend. “He’s a really aggressive player, especially in his defence.”
Harley starts for Scotland for the first time since November 2016.
Hamish Watson is fit for his first game since the Lions tour but hopes of a first cap for Rory Darge have been dashed by an ankle injury which rules out the Glasgow openside for at least a fortnight.
Another Lion, Price, starts at scrum-half, with young Dobie - born in 2001 - as back-up.
Townsend also confirmed that Fraser Brown would miss the entire Autumn Nations Series due to a knee injury while Bennett may come into contention for the final match, against Japan.