Fife's debut was confirmed by the head coach Scott Johnson yesterday when it became clear that Tommy Seymour would not recover in time from the calf problem he suffered against France last weekend.
With Max Evans also coming into the side to take the place of knee injury victim Sean Lamont on the opposite wing, Johnson finalised his matchday squad by naming Edinburgh's Jack Cuthbert and Duncan Taylor of Saracens as his outside backs on the replacements' bench.
The powerfully-built Fife has made the most of his opportunities as Edinburgh's main try-scorer since Tim Visser broke his leg last October. In one prolific burst from late November to early January, Fife scored five tries in seven matches for the club, a return that earned him inclusion in Johnson's preliminary training squad.
"We like Dougie's size and his competitive edge," said Johnson. "He chases everything, which I like, and he has shown really good glimpses playing for Edinburgh this season. He's been earmarked by us for a while and he's got his reward now.
"I don't really think Saturday will faze Dougie. He's one of those players where it doesn't seem to matter who he marks; he just goes out and plays the same."
Fife rose through the ranks of age-grade international rugby and made his Scotland A debut in last year's win against England Saxons. A former pupil of Firrhill High School - he is their first international player - he played for Boroughmuir before joining Currie while part of Edinburgh's Elite Development Player programme.
"I'm absolutely delighted and can't wait," said Fife. "The Millennium Stadium with the roof closed - I don't think it could be much better. When I got a run of games with Edinburgh and started doing fairly well I felt I could be on the brink of a Scotland call if I stuck in. I've been patient and my time has come."
Matt Scott, Fife's Edinburgh team-mate, expressed confidence in the new cap's ability to cope with what he will be up against tomorrow. "I played with him at Currie and we have come up through the age groups together," said Scott. "He has always had that talent, a solid all-round winger with that ability to beat people.
"Wales have very physical wingers and he is tall and physical so he will be a good match for whoever he comes up against. He is ready for international rugby."
After the Glasgow flanker Chris Fusaro, Fife becomes the second player to earn an international debut by Scotland during this RBS 6 Nations Championship. Astonishingly, Johnson has now introduced 16 players to the Test arena during barely 15 months in charge.
Sean Maitland, Grant Gilchrist and Ryan Wilson all became fully fledged internationalists during the 2013 Six Nations programme. On last summer's tour to South Africa, the number was swollen by the capping of Seymour, Taylor, Tim Swinson, Fraser Brown, Peter Murchie, Peter Horne, Steve Lawrie, Pat MacArthur, Greig Tonks and Alex Dunbar. In November, Jonny Gray was the only new cap.