Only forwards Hank McQueen and Adam Kleeberger and backs Jack Fitzpatrick, Mike Scholz, Conor Trainor and Duncan Maguire remain from the starting 15 that beat Uruguay 17-10 Friday night at Westhills Stadium.
Argentina plays Uruguay in the early game Tuesday. Argentina opened its tournament by defeating the Americans 27-9.
The four-team competition, which runs through Saturday, is a developmental event for the Americas.
Canada and the U.S. are fielding domestic sides, with their professionals remaining with their overseas clubs. Argentina is fielding a reserve team, with the Pumas elite squad having just wrapped up play in the Rugby Championship with Australia, New Zealand and South Africa.
Uruguay, with an eye to a World Cup qualifier looming against the U.S., sent its senior side.
With prop Andrew Tiedemann injured, prop Doug Wooldridge and No. 8 Adam Kleeberger will serve as Canada's co-captains.
Fitzpatrick shifts from fly half to fullback with Guiseppe Du Toit taking over at No. 10.
Doug Wooldridge, Lindsay RFC, Lindsay, Ont.; Ray Barkwill, Niagara Wasps RFC, Niagara Falls, Ont.; Ryan March, Abbotsford RFC, Abbotsford, B.C.; Hank McQueen, Balmy Beach, West Vancouver; Kyle Baille, Castaway Wanderers, Charlottetown, P.E.I.; Kyle Gilmour, St. Albert Rugby Club, Edmonton; Alistair Clark, Baystreet RFC, Oakville, Ont.; Adam Kleeberger, Castaway Wanderers, White Rock, B.C.; Sean White, James Bay AA, Victoria; Guiseppe Du Toit, UVic Vikes, Maple Ridge, B.C.; Jordan Wilson-Ross, James Bay AA, Alliston, Ont.; Mike Scholz, Castaway Wanderers, London, Ont.; Conor Trainor, UBCOB Ravens, Vancouver; Duncan Maguire, St. Albert Rugby Club, St. Albert, Alta.; Jack Fitzpatrick, Dublin University Football Club, Dublin, Ireland.
Micha Gorvorchin, Burnaby Lake RC, New Westminster, B.C.; Djustice Sears-Duru, Castaway Wanderers, Oakville, Ont.; Jake Illnicki, Williams Lake Rustlers, Williams Lake, B.C.; Callum Morrison, (UBCOC Ravens, Victoria; Matt Heaton, SABRFC, Godmanchester, Que.; Jamie Mackenzie, UVIC Vikes, Oakville, Ont.; Adam McQueen, Calgary Hornets, Canmore, Alta.; Joe Dolesau, Burnaby Lake RC, Burnaby, B.C.
Head coach: Kieran Crowley
Assistant Coach: Chris Silverthorn
Scrum Coach: Mike Shelley
Manager: Mark Winokur