Making his first SPL start since the opening day of last season in the 3-3 SPL draw with Motherwell, Brighton was carried off on a stretcher after catching his studs in the turf shortly before half-time, suffering a complete disruption of the anterior cruciate and medial knee ligaments.
St Mirren were already without Craig Dargo (shoulder), Mo Camara (knee) and Steven Robb (groin) for the midweek cup quarter-final against the same opponents.
Buddies (from): Gallacher, Ross, Mair, Barron, Potter, Thomson, McGinn, Dorman, Ramsey, Murray, Johnston, Mehmet, O'Donnell, Howard, Innes, McLean, Higdon, Burns.
