Now they aim to settle that score with a statement of intent to the rest of Pool A against athletic and powerful opponents at Danie Craven Stadium in Stellenbosch on Monday (June 4).
Team manager Mark Taylor said: "It would be great to put that result against Fiji to bed but the most important thing is starting this tournament with a win.
"We are in a tough and uncompromising Pool that also includes New Zealand and Samoa so we need to lay down a marker with a good performance.
"This is the Junior World Cup so we know every game is going to be tough."
Corry Hill will lead Wales who have rested Ospreys wing Eli Walker, who has had limited preparation time with the rest of the squad after featuring in the RaboDirect Pro12 Final.
Half-backs Sam Davies and Jonathan Evans get the nod ahead of Ospreys pair Matthew Morgan and Tom Habberfield while senior cap Tom Prydie also starts.
Taylor said: "There may be a few eyebrows raised that Matthew [Morgan] and Tom [Habberfield] are on the bench but that's because they have had little time with us due to their commitments with the Ospreys.
"But Sam Davies has done a great job and we have kept faith with the half-backs who served us well during the Six Nations. Dan Thomas deserves his chance in the back-row and Tom Prydie performed well in our warm-up game against Japan, as did Ross Jones.
"The great thing for us has been just how difficult selection has been. We have plenty of options in almost every position."
Harry Robinson is unavailable having joined Rob Howley's senior squad travelling to Australia following his try-scoring Test debut against Barbarians.
Wales U20s: Ross Jones; Tom Pryide, Jack Dixon, Owen Williams, Luke Morgan ; Sam Davies, Jonathan Evans; Rob Evans, Kirby Myhill, Samson Lee, Cory Hill (capt), Matthew Screech, Luke Hamilton, Dan Baker, Daniel Thomas. Replacements: Darran Harris, Gareth Thomas, Willgriff John, Rhodri Hughes, Ellis Jenkins, Tom Habberfield, Matthew Morgan, Cory Allen.