Brighton boss Roberto de Zerbi was left upset despite victory over Bournemouth on Sunday.
Kaoru Mitoma scored twice as the Seagulls won 3-1 at Falmer stadium.
But De Zerbi later said: "We played the worst game in my time.
"In two or three situations we were lucky. It is the first time we have played after a European game. We have to get used to playing a lot of games in a row. I changed a lot of players because we need to give one game on the bench for the players. We can't lose a player like Pascal Gross or Lewis Dunk the last game. We have to adapt. We didn't play well but showed character.
"We spoke at half time and that the attitude was not enough. We have to push more and attack more with intensity and be stronger.
"Mitoma is a great player for us but today we suffer without March. Gross is a unique player for us and to lose him is very tough. For new players it is tough to play with the same qualities of other players."