New South Wales star Frizell, Graham and Lafai were all hurt during a frantic first half in their side's NRL defeat to Cronulla Sharks.
Frizell went off with a head injury after a clash with Sharks winger Josh Dugan, although he was still selected by Blues head coach Brad Fittler's squad for the Origin clash in Brisbane on June 5.
Fittler, who named his team after Cronulla's victory, said of Frizell: "I went down and talked to 'Friz' at half-time and he wanted to go back on. I think he got cleared by the medical staff - obviously not to come back on but I think he is okay.
"I think that is his first concussion and we will just follow protocol. I am not sure when he can train but we will work that out."
Congratulations to Paul Vaughan and Tyson Frizell who have been named in the NSW Blues Origin squad for game one
— The Dragons (@NRL_Dragons) May 26, 2019
Graham and Lafai were reported to have ankle injuries, with a fractured fibia a possibility for the former. The duo will have scans on "suspected syndesmosis injuries", according to the club's website .
Dragons coach Paul McGregor added: "We've got a bit of a MASH unit downstairs, to be honest."
St George Illawarra are not in action again until June 10 when they take on Canterbury Bulldogs at ANZ Stadium.
Photo Getty Images. Caption: NSW star Tyson Frizell