The Scotland international was on target for the fifth successive game, converting Louis Appere’s cross in the 31st minute for his 20th goal of the season.

Appere had given United a fifth-minute lead as he lashed home the loose ball after Shankland miscued his shot from a Nicky Clark cross.

Morton levelled in the 25th minute when John Sutton headed in at the back post despite United keeper Benjamin Siegrist claiming the ball had not crossed the line.

It was a seventh successive league win for United while Morton suffered a fifth defeat in six games.