Wales back-row Ross Moriarty has been handed a four-week ban following his red-card incident in the second Test against Argentina in Santa Fe last weekend.
Wales finished the summer tour undefeated as they eased past Argentina with a 12-30 victory in the second Test at Estadio Brigadier Estanislao Lopez and wrapped up the series 2-0.
Argentina U20 have kept themselves in the race for a fifth-place finish after they managed to beat Wales 15-39 in their World Rugby U20 Championship encounter in Narbonne on Tuesday.
Wales maintained their winning momentum in June series as they eased past Argentina 10-23 in the first Test between the two teams at Estadio San Juan del Bicentenario on Saturday.
Wales managed to overcome a late try from Siosaia Fifita as they completed an 18-17 win over Japan in the World Rugby U20 Championship encounter at Perpignan.
Wales have progressed to the fifth position in the World Rugby Rankings following their thrilling 20-22 win over South Africa in their recently concluded encounter in Washington DC last weekend.