Wales Under 19 squad member James Merriman, of Hartpury College, has been drafted in to replace him, Swansea back row man Richie Pugh is set to have a scan on his injured shoulder today.
The injuries to Goode and Pugh have forced Wales coach Chris Davey to reshuffle his pack for the second Pool match against Argentina at Iffley Road, Oxford on Tuesday (kick-off 3.00pm). Wales beat Argentina 45-34 in the Pool stages in last year's competition in South Africa.
Newport lock Luke Charteris, who replaced Goode in the win over Scotland, joins Bryn Griffiths in the second row, while Cardiff's Robin Sowden-Taylor comes into the back row. Cardiff lock Chris Stamatakis and Llanelli flnaker Ioan Cunningham are drafted onto the replacements bench.
'It is a blow to lose James Goode, although we are hopeful that the injury to Richie Pugh won't force us to replace him as well,' said Davey.
'We are expecting a tough battle against the Argentinians. They won very comfortably against Canada in their opening game and had things very much their own way.
'We have developed a winning habit in recent years with Wales teams at this level and we are confident that if we play to our full potential we can do well against them and stay on course for a semi-final berth.'
Wales' third and final Pool game will be against the reigning champions South Africa at Newbury on Saturday (kick-off 6.00pm).
'The South Africans beat Ireland 36-27 in their opening game. We've chatted to the Irish coaches and they said they were a little bit unlucky to lose,' said Davey.
Wales are in Pool D with Ireland and Canada who also play against all the Pool A teams (Scotland, Argentina and South Africa). The top two teams from the combined pools will go through to the 1st - 4th Play-offs, the next two will play in the 5th - 8th Play-offs and the bottom two teams will fight it out in the 9th - 12th Play-Offs.
Wales Under 21(v Argentina): Gareth Swales (Swansea); Jonny Vaughton (Cardiff), David Bishop (Bridgend), Scott Williams (Newport), Matthew Nuttall (Pontypridd); Nick Robinson (Cardiff), Ricky Richards (Neath); Paul James (Neath, captain), Kieran Crawford (Ebbw Vale), Rhys Jones (Newport), Bryn Griffiths (Llanelli), Luke Charteris (Newport), Mark Lewis (Pontypridd), Robin Sowden-Taylor (Cardiff), James Malpas (Cardiff).
Replacements: Lee May (Swansea), T R Thomas (Newport), Chris Stamatakis (Cardiff), Ioan Cunningham (Llanelli), Alyn Lake (Bridgend), Michael Hook (Newport), Nathan Brew (Newport).