A fine, expressive one that has already booked one date at Wembley and is sweeping towards another, but also one which will begin to lose touch with the chase for a prized Champions League place should they fail to beat Arsenal on Wednesday.
Studs up: Villa's Fabian Delph and Brighton's Gary Dicker battle it out in midfield
Marc Albrighton, just 20, showed off a blistering turn of pace and matched it with calm accuracy to set up Nathan Delfouneso, two years his junior, for the opening goal in a brief 14-minute cameo before injury forced him off.
Then, after Tommy Elphick scrambled home an equaliser just before half-time and a rare Ashley Young header restored Villa's lead, another 18-year-old, Fabian Delph, displayed the exciting skills that persuaded O'Neill to part with an initial £6million.
No way through: Aston Villa's Fabian Delph (right) challenges Brighton's Elliott Benett
Slight and silky in possession, the former Leeds youngster forced a magnificent point-blank save from Brighton keeper Michel Kuipers and might have bundled home another close-range effort.
He then converted the hardest chance with aplomb when he sprinted clear, checked inside a covering defender and then swept his shot into the far corner.
A smart injury-time goal by Nicky Forster gave Brighton respectability but could not deflect attention away from Villa's new status as cup entertainers.