Finland international Forssell, who barely played last season due to a serious knee injury, has failed to find the net for City in the Premiership this campaign.
But he broke his duck with both goals in the 2-0 win over Scunthorpe on Tuesday night.
Bruce said: "We¹ve always known he can score goals and if Emile Heskey had not had the problems he's been having I don't think I would have been starting with Mikael. That is how serious his knee injury was.
"I would have liked to have nursed him back a little bit easier into it because I know that when getting over a serious long-term injury you have to be patient.
"But we've always known he can score a goal. He is off and running so I'm sure he'll score a lot more for us."