Morton slipped to fourth in the Scottish Championship table after being held to a 1-1 draw at Arbroath.
Scott Allan saw an early shot saved for the hosts, but it was Morton who took the lead just before half-time, Lewis McGrattan picking up the ball on the halfway line and driving forward before sending his shot into the bottom corner.
The hosts responded only two minutes after the restart with Daniel Fosu, who had just come on, setting up David Gold for an emphatic finish.
Robbie Crawford had the ball in the net for Morton but was denied by an offside flag, while Fosu headed wide with Arbroath’s best chance.
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