Ross Millen’s penalty proved in vain as League One favourites Dunfermline came second best to a Morton side who are expected to provide one of the biggest obstacles to their title aspirations.
Millen’s spot-kick cancelled out Declan McManus’ opener but Connor Pepper’s header sent the Pars crashing to defeat.
The Dunfermline goal scorer admitted: “Morton were difficult to play against and they played with a lot of energy but we are annoyed at our own performance.
“We didn’t seem to get our game going and that is maybe down to Morton’s efforts but we have to do more in the final third.
“With the penalty I knew exactly where I was going to hit it but we have lost the game and that’s what counts.”
Morton started positively with former Par Andy Barrowman firing over following a Lee Kilday cross.
The Cappielow side’s pressure paid off on 29 minutes when on-loan Aberdeen youngster McManus crashed an 18 yard rising right-footed volley into the Pars net from Pepper’s pass.
The Fifers almost hit back before the break when Andy Geggan rose above the Morton defence but headed wide from Lewis Martin’s free-kick.
However, the leveller eventually arrived with 18 minutes left when Ricki Lamie brought Josh Falkingham down and Millen sent Derek Gaston the wrong way from the spot.
Dunfermline only enjoyed parity for four minutes as they were caught out when Barrowman’s cross was perfectly measured for Pepper to head in the winner.
The Pars’ best chance of a second equaliser saw Michael Moffat’s shot turned behind by Gaston.
Disappointed Pars boss Jim Jefferies said: “We are annoyed to lose after getting back level at 1-1.
“At 1-1 we looked as if we were getting on top but we had deserved to be 1-0 down and Morton looked as if they wanted it more.
“They worked really hard all over the pitch to stop us getting our passing game going and it was as if we were just happy to accept it.
“On a day like this, when we did not play well, we should have been making sure we got a point after getting the equaliser.
“We needed to show more mental toughness and to make sure we were marking their player in case the ball got into the box.”
Morton boss Jim Duffy said: “This was our best performance over 90 minutes since I have been boss. It’s good for confidence beating Dunfermline.”