Giuliano gave Brazilian side Internacional a 1-0 win over compatriots Sao Paulo in the first leg of their Copa Libertadores semi-final.
The 20-year-old midfielder came off the bench for Andrezinho in the 64th minute to give the Porto Alegre side the advantage ahead of the second leg next Wednesday at the Morumbi.
Celso Roth's Inter showed more ambition during the 90 minutes at the Beira-Rio and created the best opportunities to score, most of them forged by Argentinian playmaker Andres D'Alessandro.
Only three minutes after Giuliano stepped onto the field, he got the ball from Alecsandro to beat Rogerio Ceni and net the winner. After the goal, Kleber, Taison and Alecsandro all had their own chance to widen the gap, but could not take advantage.
Giuliano stressed the importance of not conceding in the home leg. "This is small lead, but the good point is that we won and they did not score here," he said.
"Next week, they must attack a lot and we can count on counter-attacking. So we have to keep focus and continue to play as a team. That is what made the difference for us."
The winners of this tie will meet Mexican giants Guadalajara or Universidad de Chile in the two-legged final. The first leg saw those teams drew 1-1 in Mexico.