Dragons remain unbeaten

St George Illawarra have become the first team in five years to go unbeaten through the opening six rounds of an NRL season, adding insult to Cronulla's horror Friday the 13th in Wollongong.

The Sharks' 40-20 loss to their local rivals was only one concern, with Andrew Fifita and Paul Gallen sweating on knee scans on Saturday ahead of potentially lengthy stints on the sidelines.

There is particular concern over Fifita, who had his left knee in a brace amd was on crutches, sparking fears he may have damaged his anterior cruciate ligament putting his season in doubt.

Wade Graham (hamstring) and Luke Lewis (knee) will join the pair for scans after minor injuries, cutting through their star-studded forward pack and leaving them with an empty bench by fulltime.

It marks the first time since Melbourne in 2013 that a team has gone through the opening six rounds undefeated.

The Warriors have a chance to join them on 12 points on Saturday when they take on Brisbane in Auckland before the NRL's form sides meet next week.

Meanwhile a blistering opening 20 minutes has laid the platform for Melbourne's emphatic 40-14 win over Newcastle at AAMI Park.

Melbourne coach Craig Bellamy laid down the law midweek about their stuttering attack after two successive losses and the Storm responded in style.

As well as three early tries, the defending champions completed 13 from 13 sets and had 82 per cent of possession.