And the points were shared when Paul Sheerin tucked away a penalty deep into injury time.
BBC: We mugged St Mirren, says St Johnstone boss McInnes
2.
Grainger's replacement Paul Sheerin coolly stroked home from 12 yards to ensure the match ended in a draw.
BBC: St Mirren players and referee Charlie Richmond
3.
There was lengthy consultation between Richmond and assistant James Bee before O'Donnell was booked and Paul Sheerin converted from the spot to complete the scoring at 2-2.