The Round of 16 tie is on Monday evening in Porto Alegre.
"We mustn't underestimate the Algerians in any way, as the World Cup really gets going now," the Lazio striker told Bild.
"We need to be wary, because against the smaller teams even the slightest distraction can mean you're knocked out.
"If we play with our hearts, then we can go all the way. We've got to give everything to the last second.
"The reward that awaits us at the end of that road is fantastic."
For the big stories and the banter follow us on Twitter: @tribalfootball