SYDNEY, August 17, 2008 (AFP) - Melbourne Storm sounded a warning to their premiership rivals with a big win over the Sydney City Roosters in Round 23 of the Australian National Rugby League.

The Roosters went into the match eyeing top spot, but were down 20-0 at half-time after two early Anthony Quinn tries for Melbourne and were never in contention against the defending champions.

In the end the Storm won Friday's clash 30-6, their second successive win over a top-four opponent, although an ankle injury to backrower Ryan Hoffman was one downside.

Second-placed Manly suffered a morale-sapping 40-32 loss to the lowly South Sydney Rabbitohs on Sunday that put a huge dent in their premiership hopes.

Fullback Nathan Merritt scored three of the seven tries for the Rabbitohs, who ensured they would not collect the wooden spoon with the win.

Also on Sunday, the Canberra Raiders kept their playoff chances alive with a 38-18 victory over fellow finals contenders Newcastle.

With one try and five conversions, Terry Campese again lifted the Raiders, who climbed to sixth on a ladder that is looking increasingly crowded near the bottom of the top eight, while the Knights are 11th and have a tough run home to contend with.

The New Zealand Warriors beat a disappointing Cronulla 18-4 on Saturday night to stay right in the finals mix.

The Warriors are eighth after the win, with the third-placed Sharks missing the chance to climb into the top two after trailing 12-4 at half-time.

Penrith turned their form around to notch a 52-16 win over the Canterbury Bulldogs on Saturday.

Thumped 74-12 by the Raiders last week, the Panthers also stayed in the playoff race, with Luke Rooney scoring four tries.

On Saturday, Gold Coast kept their finals flame flickering by beating North Queensland 26-20.

On Friday, St George Illawarra beat Brisbane 24-20.