It needed extra time for St Clement finally to see off Trinity 4-1. The latter only had ten players and were reduced to nine when Bradley Stratford was sent off in the 64th minute after he was cautioned for the second time following a foul.
The biggest crowd of the day, of around 80 people, watched St Brelade win 3-1 against hosts St Peter.
Holders St Ouen were dumped out of the competition after they were beaten 6-0 by St Saviour at the Airport.
And St Lawrence beat Grouville 3-0 at Les Quennevais.
The semi-final line-up, to be played at Les Quennevais on Saturday 5 January. Kick off at 1.30 pm, is: St Brelade v St Lawrence and St Clement v St Saviour.