Forest won 4-1, with Morgan Gibbs-White scoring a hat-trick and Igor Jesus netting late on.
Pereira said afterwards: “Half-time, everything changed.
“We had a conversation, trying to help them find the spaces and look for different spaces. We just said to them: ‘Even if we are losing 3-0, I believe with you and our supporters we can do it; we are just losing 1-0 and just need to score two goals to win.’
"They scored four and I am very happy. The supporters deserve a lot and this win was important. But the next one is the most important because it is the next chance to get points again.”
Meanwhile Pereira admits Callum Hudson-Odoi may not play again this season.
The winger was left out of Sunday's win after being forced off in their Europa League win against Porto.
“It is a serious injury. It was very bad news for us,” Pereira said. “He had a scan and now it is trying to understand if it is possible for him to recover before the end of the season.”