The PFA served Central Coast Mariners owner Mike Charlesworth with a letter of demand following the club's decision to stand down players.
The Professional Footballers Australia (PFA) has threatened legal action against Perth Glory.
Saturday's A-League games ended in draws as doubts grow over how much longer the season will continue.
After holding a 3-0 half-time lead, Melbourne City had to weather a comeback bid from Perth Glory in an A-League thriller on Sunday.
Spectacular goals from Andrew Nabbout and Nikolai Topor-Stanley in wins for their respective sides lit up the A-League on Saturday.
Carl Robinson is still waiting for his first win as Newcastle Jets head coach after a frustrating 1-1 draw at home to Melbourne Victory.
Perth Glory remain just a point behind Melbourne City, as both sides won their respective A-League fixtures on Friday.
Adelaide United eased past Melbourne City, while Perth Glory left it late to snatch a point at home to Melbourne Victory.
Perth Glory had a penalty awarded and then ruled out by VAR as they played out a 0-0 draw with second-placed Melbourne City on Saturday.
Perth Glory beat Western Sydney Wanderers to achieve a club record, while Western United cruised to a welcome A-League win.