Melbourne Storm moved six points clear at the top of the NRL table after holding on for a tense 14-12 win over Sydney Roosters at Adelaide Oval on Friday.

Having been dropped by New South Wales for the second State of Origin game, Roosters star Latrell Mitchell had a point to prove and was at the heart of a lot of the pressure on the Storm line.

He slotted over a ninth-minute penalty but, despite Sydney dominating the early stages, Melbourne took the lead when Josh Addo-Carr broke down the left and sent Ryan Papenhuyzen over.

Daniel Tupou crossed for the Roosters after good work from former Storm star Cooper Cronk, and Mitchell then set up Joey Manu to make it 12-6, only for Melbourne's Brodie Croft to ensure the scores were level at the break.

Cameron Smith edged Melbourne in front from the tee and the Roosters could not find a way through a stubborn Storm defence as they slumped to a fourth defeat in five. The Storm have now won six on the spin and have a healthy advantage over the third-placed Roosters and second-placed South Sydney Rabbitohs.

St George Illawarra Dragons came from behind to beat North Queensland Cowboys 22-14 and move to within two points of the top eight.

The Dragons' preparation for the game was affected as players and coaches arrived late at WIN Stadium. A 10-vehicle accident that killed two people led to the M1 Princes Motorway near Wollongong being closed in both directions.

Substitute Jeremy Latimore made his way to the stadium on the back of a motorbike after abandoning his car, and full-back Matthew Dufty made it to the ground 25 minutes before kick-off.

St George then made a slow start and were 10-0 behind inside half an hour but fought back in a game marked by controversy as the Cowboys were angered by a Tariq Sims tackle that forced captain Michael Morgan from the field with a concussion.

The Dragons dominated after their early difficulties. Mikaele Ravalawa scored their opener before the interval, with Dufty, Euan Aitken and Jacob Host grabbing second-half tries.