Winger Matt Phillips said West Brom had no excuses after their 3-1 defeat at Brighton on Saturday.
The Baggies failed to get going for long periods and were 3-0 down just past the hour mark after Pascal Gross scored twice and Tomer Hemed also netted for Brighton.
James Morrison pulled a goal back but Phillips said: "It was difficult and we know we can play a lot better. We've got to dust ourselves down and get ready for next week.
"With the internationals, we've not had too much time to work on things but no excuses, we know we're a lot better than what we showed today.
"There's no easy games in the Premier League but we'll work hard this week and go again this week."