Penrith inflicted Brisbane's second straight loss in the National Rugby League, the Panthers thrashing the Broncos 33-10, while in Friday night's other game St George Illawarra edged the Bulldogs, also in Sydney.
The Dragons survived a furious second-half comeback from Canterbury to sneak home 15-10 in a tense clash at ANZ Stadium.
The Dragons scored all their points in a near flawless 15-0 first half but the machine appeared to break down in the second 40 minutes, the premiers even appearing flustered as the Dogs got physical.
Justin Hodges' State of Origin campaign is in serious doubt, after the Queensland centre suffered a suspected torn hamstring in the Broncos' big loss to the Panthers at Centrebet Stadium.
Broncos skipper Darren Lockyer also appeared in considerable pain due to a shoulder injury suffered late in the game, while Penrith fullback Michael Gordon looked to be playing his way into a NSW jersey before a potentially serious knee injury in the 70th minute ended his night.