The Panthers erased a 2-1 deficit with goals about 4 1/2 minutes apart. Goc's goal followed the tying tally by 18-year-old Aleksander Barkov, the No. 2 pick in this year's draft.
Goc's second goal was an empty-netter.
The Stars debuted new "Victory Green" jerseys and several key players, but fell apart soon after they took their first lead.
Barkov's goal came with bodies piling up around Kari Lehtonen in front of the Dallas net. The teenager found the loose puck, spun and shot it inside the left post to make it 2-2.
Goc put Florida in front when he took a centring pass from Tomas Fleischmann and beat Lehtonen with 4:55 remaining.
Tim Thomas made 24 saves for Florida.