Dragons and Newport back Lewis Robling will make his Wales Under 20 debut, partnering Owen Williams in the centre, while Eli Walker makes his first start on the left wing since he was injured in the the win over Scotland in the second game of the Under 20 Six Nations.
Webster said, "We are pleased with the strength of the side we've been able to select for this game. It's important we get off to a good start in our opening game, or we will make things very difficult for ourselves further on in the competition.
"We have watched some footage of Argentina now and as expected, they are a very physical side but we don't want to get dragged into their style of play, we want to concentrate on our own game plan and play some running rugby, weather permitting.
"Lewis Robling has done very well since coming into the squad as a replacement for Adam Warren. He is a skilful ball player and that's what we want at 12, another passing and kicking option.
"The boys have settled in well since arriving on Monday, enjoying a couple of good training sessions, despite the torrential rain all week."
Wales v Argentina Friday 10 June, Stadio Plebiscito, Padua (17.10 live coverage on S4C)
Steve Shingler (London Irish); Liam Williams (Llanelli), Owen Williams (Blues / Cardiff), Lewis Robling (Dragons / Newport), Eli Walker (Ospreys / Swansea); Matthew Morgan (Ospreys / Swansea), Jonathan Evans (Dragons / Newport); Rhodri Jones (Scarlets / Llanelli), Kirby Myhill (Scarlets / Llanelli), Will Taylor (Ospreys / Swansea), Macauley Cook (capt, Blues / Cardiff), Cory Hill (Blues / Pontypridd), Edward Siggery (Pontypridd), Thomas Young (Blues / Cardiff), Ben Thomas (Ospreys / Bridgend).
Replacements: Lewis Smout (Blues / Pontypridd), WillGriff John (Blues/ Pontypridd), Lloyd Peers (Ospreys / Bridgend), Owen Sheppeard (Blues / Pontypridd), Lewis Jones (Pontypridd), Iolo Evans (Scarlets / Llanelli)