The Reds conceded after just four minutes at the Melbourne Cricket Ground, with unmarked Christopher Ikonomidis beating Tom Heaton from inside the area.
But Ten Hag's side hit back just before the interval, with Scott McTominay's deflected effort restoring parity. Anthony Martial then notched his second goal of pre-season, following some superb link-up play, to hand United a deserved lead.
Marcus Rashford added a third with just over 10 minutes remaining, after another powerful forward run by defender Eric Bailly. Edmond Lupancu then put through his own net to round off the scoring late on.
Our Dutch boss spoke to MUTV following the win and you can read his comments below.