The Mariners finish the day as they started - a point clear of the Western Sydney Warriors at the A-League summit.
Mitchell Duke notched a first-half brace for the Mariners - one either side of Mark Milligan's penalty equaliser.
McGlinchey extended the hosts' advantage 11 minutes after the restart and, although Trent Sainsbury's own goal midway through the second half gave the visitors hope, three goals in the last 10 minutes - one from substitute Nicholas Fitzgerald and two more from McGlinchey - sealed the rout.
The Wanderers earlier extended their winning streak to seven matches and provisionally claimed top spot in the standings with a hard-fought 1-0 triumph over Perth Glory.
Tony Popovic's men dominated the first half in wet and windy conditions at Parramatta Stadium but had to wait until the 58th minute for the winner, with Aaron Mooy scoring courtesy of a deflection off Michael Thwaite.