Striker Diego Tardelli admits he is in a battle with Firmino for a starting berth in Brazil's attack alongside Neymar in the ongoing Copa America.
One of the few positions that coach Dunga is yet to finalise ahead of Brazil's Copa America opener against Peru on Sunday is the second striker, reports Xinhua.
Tardelli scored in Brazil's 2-0 friendly defeat of Mexico in Sao Paulo last Sunday while Firmino netted the winner in a 1-0 victory over Honduras in Porto Alegre on Wednesday.
"The battle is a good one," Tardelli said on Friday.
"Against Mexico it was my turn and on Wednesday Firmino entered and also played well, scoring a goal. The person who will decide is Dunga. It's his problem."
Once renowned for a seemingly endless production line of central strikers, Brazil have suffered from a dearth of attacking target men in recent years.
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And the search continues, despite Brazil's 10 straight victories since Dunga took over as the coach for a second time after last year's World Cup.
"When I came back to the national team, I was asked to observe everybody," Dunga said when questioned about 23-year-old Firmino, who plays as an attacking midfielder for Hoffenheim.
"I needed to rejuvenate the group and give a chance to players who weren't well known to the public or even the press. Everybody has made the most of their chances in their own way, including Firmino."