In 2010, Sainsbury was signed by the Central Coast Mariners where both he and fellow Central Coast Mariners team mate Marc Warren were selected to spend two weeks at Sheffield United's Academy as part of the two clubs' partnership.
In 2010, Sainsbury was signed by the Central Coast Mariners along with Sam Gallagher. Trent and Mariners teammate Marc Warren were selected to spend two weeks at Sheffield United's Academy as part of the two clubs' partnership.