Jack Baird’s early goal was the difference as Morton beat promotion hopefuls Dundee 1-0.
Back-to-back league wins see Morton stay fourth in the cinch Championship table, while the Dee remain second.
The game’s decisive moment came six minutes in when a corner was whipped in and Baird headed home.
The hosts continued to press and Cameron Blues forced a good save from goalkeeper Adam Legzdins before Dundee reacted quickly to clear the ball off the line from a corner.
Brian Schwake was then called into action for Morton to deny Alex Jakubiak and Josh Mulligan had a chance towards the end of the first half but his curling effort went wide.
Morton nearly made it two after the restart when Jai Quitongo’s shot smashed off the bar before Darragh O’Connor’s follow-up was deflected and Schwake then made another good stop from Mulligan’s strike.