Penrith and Newcastle have rocketed to the top of their group with resounding victories in day one of the NRL Nines at HBF Stadium in Perth.

In searing heat, barnstorming second-rower Viliame Kikau was unstoppable for the Panthers, scoring two tries in their 35-0 win over the understrength Roosters.

Spearheaded by the return of former skipper Kurt Gidley, the Knights put away the Warriors with a 34-0 win to sit behind the Panthers at the top of the pool.

Gidley, 37, was slick in his return to the game just two years after he retired from professional rugby league with Warrington.

Canterbury shocked competition favourites Parramatta with a 13-10 win off a late try from NRL hopeful Morgan Harper, his second for the afternoon.

St George Illawarra also scored an upset against tournament heavyweights Cronulla with a 27-5 win, while the Gold Coast started life under new coach Justin Holbrook with a 21-10 win over Canberra.

To finish the first day of the tournament South Sydney will play the Wests Tigers and North Queensland face Brisbane before Melbourne take on Manly.