Ward and fellow substitute Mirjan Pavlovic each had a couple of shots blocked before the ball fell kindly for Ward who fired home from close range.
While Mark Paston eventually savoured a second straight clean sheet there was always the feeling that the visitors were good for a goal which could have thrown Phoenix hopes into disarray.
While not on the back foot as much as they were in snatching that 1-0 away win over Sydney eight days earlier, the Phoenix should have done better against a United side who travelled only after a late court injunction (on Friday night) cleared the way for the game to proceed.
Missing key players and with stand-in coach Mike Mulvey forced to give more youth a chance - he put out a team with an average age of just 23 years - the visitors battled bravely. On the wrong end of a 16-4 corner count and forced to defend a number of Phoenix attacking freekicks, Gold Coast refused to yield - led by a brave display from Tyson.
Forced to rejig to cover for the absence of an ailing Tony Lochhead, the Phoenix were not as settled as they have been with Vince Lia taking the left-back role and Alex Smith given a reprieve in midfield.
While Bertos ensured a good supply of ball from the flanks his efforts led to little as Paul Ifill and Chris Greenacre were given no change by a resolute defence.
There is no time for the Phoenix to reflect. They now head to Melbourne where they will stay for a week as they take on the Heart and then the Victory - two teams battling for a place in the play-offs.
A win over the Heart this Saturday would give the Phoenix a big enough buffer to almost certainly cement their spot in the playoffs.
A loss would throw the scramble wide open, especially if fourth-placed Perth Glory can upset leaders Central Coast Mariners on Sunday.