Centreback Joy has emerged as United's most improved defender, and was picked in the ASB Premiership team of the month at the end of last season.
University commitments preclude the tall defender from playing tomorrow, which will have had new coach Luiz Uehara scratching his head regarding team selection.
New German defender Jacob Schneider is also doubtful due to a cut eye he sustained in last week's 5-1 loss to Canterbury in a warm-up game in Timaru.
Southern's most experienced midfielder, Patrick Ebanda, has also been under an injury cloud, receiving regular treatment from club physiotherapist Dusty Quinn, who is emerging as a key factor in the build-up for tomorrow's clash with last year's champion.
Ideally, Uehara would like to have confirmed and worked with his starting XI, but last week there were five players unavailable due to university exams, and as a measure of the flux that still exists, outsider Campbell Higgins may have played himself into contention after a strong performance against Canterbury.
Compared with the same fixture last year, when Waitakere won 4-1, there are 11 players from that Otago team missing: Liam Little, Ant Hancock, Matt Joy, Jude Fitzpatrick, Victor da Costa, James Govan, Scott Gannon, Tom Connor, Tim Horner, Zayne Officer and Craig Ferguson.
To compensate, Uehara and and assistant Darren Hart have signed Schneider, Brazilian striker Henrique Viana and former Canterbury keeper Tom Batty, who all have been showing out well in some intensive training sessions this week to build understanding and team spirit.
''Clearly, we are still building our team shape, and strategy, which does not happen overnight,'' Uehara said.
''But we are making progress, and individually as players, several of the squad look to me to have the potential to play at even international level. They have tremendous potential.''
Southern strikes a tough opening opponent in Waitakere, which has won the past four finals.
But the Auckland club also has a few question marks, as new player-coach Brian Shelley examines his options after losing the Charity Cup 4-1 to Auckland City.
''We have lost some key players,'' Shelley said.
''We know it is going to be a bit of a rebuild on and off the pitch but that is a challenge we all accept and look forward to meeting.''
A Uefa B coaching badge-holder, Shelley has played in Ireland and England at the highest level, in both the Uefa Cup and Champions League, and has also been capped at youth level for Ireland.
The task is clear for a new-look Southern United side. Pinching advice from Sir Alex Ferguson to a young defender: ''Just win all your tackles, son, challenge strongly for headers, and when you win the ball - pass it to one of us.''
Good advice, with the emphasis on not giving the ball away cheaply, and hoping for the likes of Viana or Regan Coldicott to grab a goal for the home side, and switch pressure on to Waitakere.
ASB Premiership: Forsyth Barr Stadium, tomorrow, 1pm
Southern United: Tom Batty, Jeferson Potrich, David Hayman, Jacob Schneider, Peter Overmire, Campbell Attwood, David Low, Nicki Hindson, Patrick Ebanda, Henry Flood, Morgan Day, Sam Mepham, Aajay Cunningham, Andrew Ridden, Regan Coldicott, Taylor McCormack, Geordie Mansford, Peter Rae, Daniel Morris, Henrique Alves Viana, Campbell Higgins.
Waitakere United: Danny Robinson, Ryan Howlett, Alec Solomons, Tim Myers, Brian Shelley, Matt Cunneen, Jordan Lowden, Chad Coombes, Sam French, Richie Cardozo, Ian Hogg, Sam Mathews, Jack Hobson McVeigh, Sansern Limwatthana, Daniel Morgan, Jack Caunter, Tristan Prattley, Dylan Stansfield, Sean Dowling.
