Shankland netted in the 77th minute as United opened their Premier Sports Cup campaign with a 1-0 win over league newcomers Kelty Hearts at New Central Park.
Shankland slotted home from six yards after Kieran Freeman's accurate first-time cross had set him up.
Kelty were also under new management after Kevin Thomson replaced former Rangers team-mate Barry Ferguson following their promotion, and they started well against their Premiership visitors.
Joe Cardle forced two saves in quick succession from United goalkeeper Benjamin Siegrist before Nathan Austin headed over.
Shankland and Nicky Clark saw efforts saved by Darren Jamieson and the Kelty keeper denied the latter again after the break after a direct run by substitute Logan Chalmers led to a good chance.
Kelty looked set to deny their former boss Courts a winning start but Shankland struck after Jeando Fuchs played a lofted ball which got Freeman in behind.
Kelty pushed hard for an equaliser but could not trouble Siegrist.
In the other game of the night, Callum Smith hit the only goal as Hamilton won 1-0 away to Edinburgh City.
The forward struck in the 24th minute after a one-two with Kieran MacDonald and also hit the bar with an overhead kick in the second period.