The rampant New Zealand Warriors were the big movers as reigning premiers the Sydney Roosters assumed title favouritism after the opening round of the National Rugby League finals series at the weekend.

The Roosters' 36-8 elimination of Newcastle at Aussie Stadium had Centrebet push Ricky Stuart's men into $2.50 favourites to successfully defend their premiership.

But the Warriors' 48-22 dismantling of the Bulldogs at Sydney Showground has prompted the leading bookmaking agency to dramatically wind the flamboyant New Zealanders in from $15 to $4.75 to capture their maiden title.

Centrebet has taken a flood of bets on the Warriors since Friday and stands to drop another $100,000 if the Kiwis go one step better than last year's grand final defeat.

"There's been a constant stream of money for them, most of it from New Zealand. So they certainly think they can win, anyway," Centrebet manager Gerard Daffy said.

The Bulldogs, who had headed the betting market for much of the latter half of the season, have drifted from $2.75 favourites on Friday to $4.75 equal-third picks following their second-half capitulation against the Warriors.

Penrith is the second fancy at $4.25 after backing up its minor premiership with a 28-18 dismissal of Brisbane at Penrith Football Stadium.

Melbourne and Canberra remain the outsiders after the Storm's 30-18 win over the Raiders in Canberra on Friday night.

Full Centrebet market, with last week's betting in brackets, is:

Sydney Roosters $2.50 ($3.75), Penrith $4.25 ($5.50), New Zealand Warriors $4.75 ($15), Bulldogs $4.75 ($2.75), Melbourne $13 ($21) and Canberra $17 ($11).

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