Albion's under-18s lost 2-0 at Millwall this morning in a hastily re-arranged Youth Alliance fixture.
The Seagulls were due to face the Lions this coming Saturday, but the game was brought forward because both sides are in involved in FA Youth Cup ties early next week.
Millwall striker Jon Marquis struck either side of half-time to give the Londoners victory.
The game was Albion's first run-out for two weeks, during which time the squad's training regime has also been severely disrupted by bad weather, and boss Steve Brown admitted his side looked rusty.
"I don't really want to use our lack of action as an excuse for the defeat, but it was blatantly obvious that we were a yard off the pace.
"Millwall were sharper than us, got to second balls quicker than us, and our performance was below par compared to the standards we have set ourselves this season.
"But it was great that we could get the game on, blow the cobwebs away and now we can look forward to Northampton next week."
The Seagulls received a huge boost ahead of that FA Youth Cup tie after Mitch Walker played his first game since breaking his wrist in September. He was replaced after an hour as a precaution.
Albion: (4-4-2) Walker (James 60); Cooper, Sheriff (Dunk 60), Hall, Smith; Redwood, Thomson, Hayward (Wilkins 60), Bolwell; Hider, Barker. Sub not used: Woodley.
