A Danny Welbeck penalty and Brajan Gruda goal earned Brighton the points on Saturday.
Pereira said afterwards: “In my opinion, two different parts. The first half we competed, created some chances to finish, but missed the last shot, last pass, but we competed with one or two mistakes. Second half, in my opinion, we can do better. We tried to turn over the result. A lot of heart, but we missed some organisation.
“The game started to become unpredictable, very open, and we exposed ourselves to counter attacks against a good team. They finished and they scored the second. We had the chance to score before 1-1, but they scored the second.
“We played a lot with our heart in the second half, but without intelligence to control the pace and the match goes to transitions and transitions, counter transitions. We won the ball, lost the ball. This is not the game that I like, because it's unpredictable. In the end, they punished us, and they deserved the win.”
No slacking off
Pereira insists the season cannot be allowed to peter out.
“This is something that we need to correct, not only the tactical things, but the mental things. The last game against City, I watched a team organised, compact, aggressive.
"We didn't finish the season. We need to keep our level and to compete for the three points in next two games.”
The manager also handed 17 year-old striker Matheus Mane a debut and added: “He's a player with talents for sure. He will be in our team next season, in the first-team, because he has the quality and the talent to be.”