Allan Moore welcomed Mark McLaughlin and long-term absentees Kevin Rutkiewicz and Martin Hardie back into the fold after injury.
Rutkiewicz, rather surprisingly, started - and it was the defender who gave Ton the lead in the 14th minute when he glanced Michael Tidser's inswinging corner into the net.
The advantage lasted just six minutes, however, as Steven Craig hooked home from eight yards after Tidser miscued a headed clearance from Aaron Muirhead's long throw.
Partick demonstrated just why they are the First Division early pacesetters in the remainder of the half with some flowing, attacking football.
But it was the hosts who went in at the break ahead when skipper McLaughlin powered home another Tidser corner to score a carbon copy of his central-defensive partner's opener.
The odds looked stacked in Morton's favour when Hugh Murray was shown a second yellow card for a crunching foul on Stephen Stirling, which saw the midfielder stretchered off and taken to hospital in an ambulance.
Jackie McNamara's side refused to adapt their philosophy despite going down to 10 men and continued to look threatening until David O'Brien wrapped up the win four minutes from time.
The winger was put clear by sub Hardie and finished with aplomb to ensure his side would move to within two points of their opponents and new table toppers Dunfermline.
Ton boss Moore said: "That was a hard-fought win. The manner in which we won was pleasing. We dug in.
"Thistle probably played the better football - but these games aren't about playing the better football, it's about winning them."
Morton (4-4-2): Gaston; Reid, Rutkiewicz, McLaughlin © (Naismith, 79), Dyer; Stirling (Graham, 59), Bachirou, Tidser, O'Brien; Campbell, Weatherson (Hardie, 73).
Subs not used: Wallace, Hutton (gk).
Booked: Rutkiewicz (45), Bachirou (66).
Partick Thistle (4-3-3): Fox; O'Donnell, Muirhead, Archibald, Bannigan; Paton, Murray, Forbes (Slane, 69); Erskine (Sinclair, 59), Craig, Lawless (Doolan, 69).
Subs not used: Elliott, Scully (gk).
Booked: Murray (37, 55), Paton (67), Bannigan (82).
Sent off: Murray (55).
Referee: Des Roache