Mitchell Moses says he and Jarome Luai have spoken regularly before the premiership-winning playmaker joins Parramatta.
Australia selected Moses as one of four halves for the tournament, alongside Cameron Munster, Sam Walker and Tom Dearden.
He is due to wear the Australian No.7 jersey for the first time against New Zealand on Thursday, following what he called an unexpected call-up.
Moses travelled to England with the Kangaroos last year as an "Emu", a non-playing squad member.
Nathan Cleary would have been an automatic selection for coach Kevin Walters, but suffered a double compound fracture of his leg in Penrith's preliminary final loss to Newcastle.
Cleary's injury created an opportunity for Moses.
"I thought that time had passed, so it's a great feeling," Moses said of his selection.
"I just can't wait to get out there [Thursday] night and represent the country."