Italian coach Roberto De Zerbi has admitted Brighton are struggling with too many games this season.
The Albion have lost Solly March to what could be a long term injury at the weekend.
March was injured in Brighton's 2-1 loss to champions Manchester City in the Premier League.
Post-game, De Zerbi said the following about how the Europa League is impacting his squad: "This is the worst thing today. We can lose Solly March for a long time and Welbeck I don't know.
We are playing a different sport this season. We are losing too many players. I think we are not ready to compete in this competition and we are adapting."
Asked about the game against City, he added: "We can speak of two parts of the game.
The first part there wasn't the chance to play, because when City play like they do in first half it is not just very tough for Brighton but for everyone.
"But second half we played better, with more energy, courage and personality. We kept order on the pitch, especially without the ball and we had two or three chances to score again. That improvement is important."