Morton ended a 17-year wait for a league win over St Mirren thanks to a 3-1 victory at Cappielow on Tuesday night.
The Greenock men had gone 12 Renfrewshire derbies without success since a 5-1 triumph in April 1999 but ended that barren run in style.
Thomas O'Ware, Ross Forbes and Gary Oliver got the goals for a dominant home side before Ben Gordon pulled one back late on for the Buddies.
It was a fourth straight win in the Ladbrokes Championship for Jim Duffy's men and takes them into the play-off places while Saints remain at the foot of the table and are still seeking their first league victory of the season.
