Moltzen suffered an ACL injury to his left knee the same knee he did in 2010 in the second half. Centres Chris Lawrence (hamstring) and Blake Ayshford (ankle) also left the field which saw Wests Tigers finish the game with 12 men in front of a crowd of 11,547.
Brisbane opened the scoring in the 5th minute when full-back Corey Norman sliced through a large gap to beat half-back Tim Moltzen to score out wide. Five-eighth Scott Prince converted for a 4-0 lead.
It became 8-0 after 11 minutes when the ball was spread right for second-rower Matt Gillett to go through another big hole after winger Matt Utai rushed up in defence to score out wide. Prince failed to convert the try.
The Broncos went to a 12-0 lead in the 27th minute when Gillett scored his second try after centre Justin Hodges popped a ball out the back in a three man tackle for the second-rower to score. Corey Parker converted for a 14-0 lead.
Wests Tigers opened their account in the 39th minute when hooker and captain Robbie Farah was twice involved in the play that led to winger Matt Utai burrowing his way over the tryline. Moltzen failed to convert the try to leave Wests Tigers trailing 14-4.
Wests Tigers soaked up some enormous pressure in the opening seven minutes after the Broncos had consecutive sets at their tryline.
The video referee was called upon in the 58th minute when a grubber kick from Farah saw the ball bounce off the pads for forward Sauaso Sue to scoop up the ball to score. It was awarded no try on the basis of a double movement.
Two minutes later, Moltzen left the field with the knee injury.
Wests Tigers got back to 14-8 when a Farah kick saw the ball bounce and hit the crossbar. Norman dropped the ball for Shaun Spence to score his first try in the NRL. Curtis Sironen converted the try for a 14-10 scoreline.
Ayshford then left the field with his ankle injury before Hodges scored a late try out wide to seal victory. Parker converted for the 20-10 scoreline.