Alan Lithgow scored twice for the hosts and played his part in setting up the other as David Hopkin’s side responded to losing the opening goal to Thomas O’Ware to remain six points clear in second.
Morton’s lead was cancelled out in the 35th minute. Lithgow’s long throw was flicked on by Lee Miller and Jackson Longridge stole in at the back post to head home.
The hosts were rewarded for a bright start to the second period by taking the lead. After Ryan Hardie’s drive was saved by Derek Gaston, Lithgow rose to head in Jordan Thompson’s corner.
Morton hit back in the 69th minute as Ricki Lamie rifled home only his second goal for the club from a Michael Tidser corner.
However, Lithgow nodded in his second from sub Keaghan Jacobs’ corner four minutes from time.