The striker could have helped himself to a hat-trick, but his performance was acknowledged by the home support, who gave him a warm ovation when he was substituted late in the game.
He had an early effort cleared off the line by Stuart Findlay, but took just 13 minutes to make his mark, heading an excellent cross from Martin Boyle beyond Derek Gaston.
Morton had their moments, but lacked conviction in front of goal when chances came their way, with Rowan Vine and Garry O'Connor shooting directly at Kyle Letheren in the first half.
Nade shot narrowly wide midway through the second half when he fashioned an opportunity for himself, and perhaps should have done better.
But Peter MacDonald ensured there was no way back for Morton with his 17th goal of the season with just four minutes remaining.
Hamilton kept on Dundee's coat-tails, a splendid 3-0 win at Alloa Athletic keeping them to within a point of the leaders.
The hard work was all done in the first half with Hamilton three goals to the good by half-time.
A mistake by Scott Bain, the Alloa goalkeeper, presented Louis Longridge with the opening goal after barely 30 seconds.
The Lanarkshire side doubled their advantage after 10 minutes when James Keatings netted his 14th goal of the season from the penalty spot.
Tony Andreu made it 3-0 after 19 minutes with a low shot after Alloa again looked unconvincing at the back, and that was the end of the scoring.
Ali Crawford struck the underside of the crossbar late in the first half and Alloa could not find a way back in the second half.
Falkirk won 4-2 at Raith Rovers, who have now gone 10 games without a victory, to maintain their challenge.
Falkirk took the lead early on through a bizarre own goal from Dougie Hill, but Raith led at half-time through a John Baird header and a Callum Booth penalty.
David McCracken's close-range effort restored parity for the Bairns just after the restart and they edged in front through Rory Loy before a superbly struck free kick from Millar late in the game sealed the three points.
Queen of the South hurdled Dumbarton into fourth with a 3-1 win over Ian Murray's side at Palmerston.
Mark Durnan headed the opening goal from a free-kick and Gavin Reilly scored the second on the stroke of half-time after a corner.
Bob McHugh added the third midway through the second half before substitute Michael Miller pulled a goal back for Dumbarton.
Livingston beat Cowdenbeath 1-0 in a scrappy contest at Almondvale.
Thomas Flynn produced an acrobatic save to keep out Keaghan Jacobs but was beaten after 63 minutes when Jason Talbot slid in at the back post to convert a Michal Habai cross for the only goal.