Chelsea has now three opportunities to play against teams that are not in top shape in the Premier League. Perhaps this win against Dortmund now gives them a push and they can improve. If they started a winning streak now of three consecutive games, they would afterwards host the game against Liverpool and that could be their final chance to keep a realistic probability for the qualification for the international ranks in the table. I doubt that they can still make it 1-4, but if they win a lot of games the Europa League could still be achievable.