The Broncos set up a top of the table showdown with the Dolphins after piling on four tries in nine minutes to beat the Dragons 40-18 at Suncorp Stadium.
The Broncos trailed 16-8 at halftime and the scores were locked at 18-18 until the 71st minute but they finished too strong to ensure an epic build up to the historic clash with their new cross-town rivals on Friday night.
However, a two-point field goal on the last play of the first half by Broncos captain Adam Reynolds narrowed the deficit to 16-8 at the interval and it was a different game after the break.
Staggs got his second try in the 50th minute after gathering up a Reynolds grubber kick and juggling the ball before regaining control and performing a forward roll as he ground the ball in the Dragons in-goal.
A try saving tackle by Sloan denied Cobbo and the Dragons appeared to have steadied when Mikaele Ravalawa burst through the defence from the backfield.
Zac Lomax won the race for a deep kick from Ben Hunt, only for the try to be disallowed after replays showed he had put his hand on the touchline as he ground the ball.
Cobbo was finally rewarded when he scored eight minutes before fulltime after Reynolds feigned to kick and passed to fullback Reece Walsh, who turned the winger back inside to cross near the posts.
Source: NRL.com
