Relegation-threatened Sirens had to settle for a point despite dominating much of the game against a Mosta side who finished the match with nine men.
Samba Tounkara missed two good chances to put them ahead and Hamed Kone also went close from close-range.
Mosta are now almost safe from the drop, after gaining four points from two direct encounters in a space of few days.
There were two changes in the Mosta formation, with Kevin Tulimieri came in for Mathias Muchardi and William Donkin got the nod ahead of Christ Ememe.
For the Northenders, Kone was back in action.
Giovanni Tedesco, the Sirens coach, appeared to have no inhibitions as he presented a three-pronged attacking formation made of Kone, Wilfried Domoroud and Samba Tounkara, constantly supported by Lamin Bittaye.
Mosta were just as disposed to go for enterprise with Michael Mifsud flanking the big-frame of central striker Bojan Kaljevic and a slightly deeper-lying Donkin.