A last-minute winner from Jake Robinson put Albion under-17s within one win of the Youth Under-17s Alliance title.
Robinson struck his 17th goal of the season in the second minute of stoppage time to secure a 2-1 victory at Portsmouth. Ben Watson scored their other goal.
Manager Dean Wilkins said: "It was a poor performance but the result puts them in a great position."
Albion meet Cambridge United and Luton in their final two matches.
Seagulls were due to face United on Saturday but their hosts postponed the match because of a waterlogged pitch.
Wilkins said: "That was a strange one. I didn't think there was that much rain around on Saturday."
Their nearst rivals, Peterborough, could only draw 0-0 with Southend.
If third-placed Orient beat Cambridge in their next game, Albion will need two points for the championship. If Orient fail to win the target is one point.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article