For the Malta international, this was his third league goal of the season.
Muscat, on his 22nd appearance for the club in this campaign, put his side ahead on the half-hour mark with a close-range finish following a corner-kick situation.
Feirense levelled terms after the interval as Casa Pia slipped into second place with 53 points – one behind leaders Rio Ave.
Their next league commitment is an away match against Academica Coimbra, following the men’s international break.
