Parker suffered a knee injury during practice on Wednesday, but an MRI showed no damage and the 22-year-old has responded well to treatment. Tardits was thought to be out of the competition due to a family illness, but his father's steady progress after surgery allowed him to join the team.
But flanker and captain Dan Lyle (knee) and lock Luke Gross (hand) remain shelved due to recent injuries, and the absence of three more starters from the USA's last match, a handy win over Japan on July 6, means that stand-in captain Chris Lippert still faces a difficult task in trying to lead the Eagles to their first-ever win over Argentina.
Recalled to the national team, lock Bill Leversee shores up a forward unit that also includes hooker Tom Billups and number Rob Lumkong, while the backline features a new wrinkle. Pacific Rim try-scoring leader Vaea Anitoni spearheads the offense from his spot at right wing, but Juan Grobler earns his first cap at center, and Ed Schram moves from his accustomed place in the midfield out to left wing.
"After finishing second in the Pacific Rim series and getting a lot of new guys some experience, we're quietly optimistic," Lippert said in anticipation of tomorrow's contest.
Host Canada tackles Uruguay following the conclusion of the US-Argentina match.
United States: Maika Sika; Vaea Anitoni, Juan Grobler, Mark
Scharrenberg, Ed Schram; Matt Alexander, Andre Bachelet; Chris
Lippert (captain), Tom Billups, Ray Lehner, Bill Leversee, Alec
Parker, Rob Randell, Richard Tardits, Rob Lumkong.