The 22-year-old from Williams Lake, is one of four changes made by Canadian coach Kieran Crowley for the game, expected to be played in searing heat at Bonney Field.
Andrew Tiedemann comes in at the other prop position with Hubert Buydens and Jason Marshall, who started in the 19-17 loss to Scotland at BMO Field last week, moving to the bench.
"They've both played really well when they've come on," Crowley said of the new prop pairing. "We feel as though they deserve an opportunity to start and we'll see how it goes."
Ilnicki played for Canada A in the 2013 Americas Rugby Championship and saw action for Canada against the New Zealand Maori in November that year. He won his first official cap against Georgia that same month as a second-half replacement for Tiedemann.
At 19, Ilnicki spent a season in New Zealand with an Auckland club team.
"He's a young player who's really progressed well," Crowley said. "We've been really impressed with his training. He was chucked in the deep end last year against Georgia really and he held up very well there when he came on against some world-class props. He's just developed further from that.
"Before the Japan game (on June 7) there was a lot of debate around the front row and the props and that. Both Marshall and Buydens have done very well but it's an opportunity in this game as we look towards the future to see how Andrew and Jake go."
Tiedemann, a 25-year-old from St. Albert, Alta., won his first cap against Wales in 2009.
In the backs, Connor Braid replaces Nick Blevins at inside centre and DTH van der Merwe comes in for injured winger Taylor Paris (concussion).
"We feel Connor's made a real impact when he's come on and we just want to see, from a further on down the path point of view, his abilities as a starter at No, 12," said Crowley
Paris was hurt in the loss to Scotland, opening the door for Van der Merwe, who is coming back from a shoulder injury.
The rest of the side remains the same, with back-row forward Jebb Sinclair escaping further punishment after a disputed red card in the Scotland game.
Canada, ranked 16th in the world, and the No. 18 U.S. Eagles were both beaten by No. 12 Japan in their opening games of the tournament. Canada lost 34-25 in Burnaby, B.C., while the Americans went down 37-29 in Carson, Calif.
The two North Americans sides were also beaten by Scotland, who opened their summer tour with a 24-6 victory over the Eagles in Houston.
The Canadians hope to extend an eight-game unbeaten streak against the Americans that included three straight wins in 2013. Canada won a two-match World Cup qualifying tie by 20 points last summer after taking a 16-9 decision over the Eagles in May in Edmonton.
The U.S. has not defeated Canada since a 12-6 win in July 2009 in South Carolina. That was the first leg of a World Cup qualifying series and the Canadians won the return match 41-18 a week later to book their 2011 tournament ticket.
Kickoff at the new 8,000 seat stadium is 3 p.m. PT Saturday.
Andrew Tiedemann, Plymouth Albion (England), St. Albert, Alta.; Aaron Carpenter, Cornish Pirates (England), Brantford, Ont.; Jake Ilnicki, Williams Lake Rustlers, Williams Lake, B.C.; Jamie Cudmore, ASM Clermont Auvergne (France), Squamish, B.C.; Tyler Hotson, London Scottish (England), Vancouver; Jebb Sinclair, London Irish (England), Fredericton; John Moonlight, James Bay AA, Pickering, Ont.; Tyler Ardron (capt.), Ospreys (Wales), Lakefield, Ont.; Phil Mack, James Bay AA, Victoria; Harry Jones, Capilano, West Vancouver; DTH Van der Merwe, Glasgow Warriors (Scotland), Regina; Connor Braid, James Bay AA, Victoria; Ciaran Hearn, Castaway Wanderers, Conception Bay South, N.L.; Jeff Hassler, Ospreys (Wales) Okotoks, Alta.; James Pritchard, Bedford Blues (England) Parkes, Australia.
Hubert Buydens, Manawatu Turbos (New Zealand), Saskatoon; Ray Barkwill, Niagara Wasps, Niagara Falls, Ont.; Jason Marshall, Atlantique Stade Rochelais (France), Vancouver; Jon Phelan, Doncaster Knights (England), Montreal; Kyle Gilmour, Saint Albert RFC, Saint Albert, Alta.; Gordon McRorie, Calgary Hornets, Calgary; Nathan Hirayama, UVIC Vikes, Richmond, B.C.