The Brazilian teed up Naby Keita for a deflected opener in the Champions League quarter-final at Anfield and then sealed a flowing Reds move from close range to secure a 2-0 advantage before the break.
Jürgen Klopp’s side were unable to add to the scoresheet in the second half, while Porto passed up several promising opportunities to claim an away goal.
So the tie remains in the balance ahead of the return at Estadio do Dragao next Wednesday – and Firmino insisted nobody should take that match for granted.
“It was an important victory. We’ve taken the first step,” the Liverpool No.