Holger Osieck
In May 2013, Trent was selected in a Socceroos Australian-based training squad for upcoming World Cup qualifiers. In July 2013, he made Australia's squad for the 2013 EAFF East Asian Cup. Despite strong club form, Sainsbury was the only outfield player in the squad not to be used by coach Holger Osieck in the tournament, which he suggested may have been due to Osieck mistaking his laid-back attitude for a lack of commitment.