Roberto De Zerbi said many key elements were out of his control before his Brighton team lost 3-0 at Fulham.
De Zerbi left a number of key players on the bench at Craven Cottage.
Albion went into the game without Joao Pedro (thigh), James Milner (thigh), Solly March (knee), Kaoru Mitoma (back), Jack Hinshelwood (foot) and Billy Gilmour (suspended)
It was therefore a surprise to see Igor Julio, Pascal Gross, Danny Welbeck, Simon Adingra, Ansu Fati and Facundo Buonanotte all on the substitutes’ bench.
“We have to find right first XL every game,” De Zerbi said. “To find the right energy. Without it, it’s impossible to compete at this level.
“We had JP [Jan Paul van Hecke) in midfield position because [Jakub Moder] played 60 /70 minutes in Wolverhampton.
“Pascal Gross finished the [FA Cup] game with cramp and couldn’t start the game and play 90 minutes.
“Adingra played in Africa Cup of Nations. Then he played 90 minutes three/ four games in a row. Facundo as well. We can’t lose any other players or we can’t play.
De Zerbi said ‘many things’ went wrong in the defeat at Fulham.
He added: “We didn’t play well. We deserve to lose the game.
“Fulham played a good game. Not an amazing or incredible game but enough to win 3-0 and they deserve to win 3-0.
“We played without energy and in the Premier League you need to do that. You can’t play 50 / 60 per cent.”
The Italian said Brighton ‘have to move on’ and to ‘play and fight better’.
“We need to play with different energy and find right motivation,” he said.
“In the last months of the season, we play a crucial part of the season with a lot of problems. We have the possibility to play better and we have to do that.”