The quarterfinal is on a knife-edge after the first-leg draw in Portugal.
Pereira said at the final whistle: "A good result in my opinion. To face two competitions we need to play with everyone. The players that started today did good work. In the end, 1-1, the game is open to play at home and decide qualification.
"Porto playing at home are a strong team. They have momentum with supporters. Forest I try to balance the two competitions, it was very clear we played with nine different players to the last game. I think we did well. The players tried everything. 1-1 is a good result and playing at home we will see what we can do."
On Forest's disallowed goal, he smiled: "It is better to keep the opinion with me."
Asked about Forest's squad depth, Pereira concluded: "The first two subs we did I was thinking about the next game against Villa. It's very important for us to get points in the league and this is the only way."