The Phoenix team is in its first year of ASB Premiership football. Essentially a youth team with some senior reinforcements, it includes Mosgiel product James McGarry and former Green Island striker Joel Stevens.
Dubbed the ''Wee Nix'', the team is permitted to field four A-League professionals, so fringe first-teamers Michael Boxall, Vince Lia, Louis Fenton and Kenny Cunningham could be included.
New All Whites keeper Oliver Sail, Alex Rufer and Matthew Ridenton will probably head the youthful contingent.
So far, the Phoenix has played three games, beating Wanderers 3-0 and sustaining 2-1 losses to Wellington and Waitakere.
Southern United coach Mike Fridge now has a full complement of players after a worrying period that was full of injuries.
Tom Connor was the last to get the thumbs up after a strong training session this week.
The only long-term injury remaining is centreback Matt Joy, who looks likely to be out for some time and could face surgery.
''It's not often our players get a chance to play against fulltime professionals, so the squad is looking forward to that challenge,'' Fridge said.
''Senior Phoenix players will be looking to impress coach Ernie Merrick and try to play their way back into the first team, so the blend of quality youngsters and seasoned professionals should make for an interesting contest.''
If the Southern coach has a problem, it is the lack of match fitness and sharpness that comes from recent byes and layoffs.
''We may have to look at midweek matches against our youth team to regain sharpness on the ball, and realistic match conditions.''
After two gameless match days due to byes and rescheduling, United has played only three games, two of which were in Dunedin.
After the Invercargill match, United faces three games on the road, against Wellington, Hawkes Bay and Wanderers.
The next home fixture will be against Waikato-BOP on January 11.
With two wins, over Canterbury and Waitakere, Fridge is keen to get his side back into the fray and possibly improve a fourth placing, which has been achieved by playing a game fewer than the top three.
Also seeking improvement is Southern's youth coach, Kevin Scoullar, who, although pleased with his young team's progress, is disappointed that four drawn matches have caused a slide down to mid-table.
Southern's youth team is on the road tomorrow for a difficult match against the second-top Nelson Falcons.
Southern v Phoenix
Invercargill, tomorrow
Southern United: Tom Batty, Ross Howard, Craig Ferguson, Campbell Attwood, George Milne, Taylor McCormack, Eder Franchini, Andrew Ridden, Tom Jackson, Victor Da Costa, Joshua Stewart, Tim McLennan, Tom Connor, Nicholas Hindson, Joshua Dijkstra, Alistair Rickerby, Jude Fitzpatrick.
Wellington Phoenix: Oliver Sail, Alex Rodriguez, Joe Bell, Tyler Boyd, Alex Rufer, Matthew Ridenton, Joel Stevens, Andrew Blake, Tamupiwa Dimario, James McGarry, Sam Wilson, Nathaniel Hailemariam, Justin Gulley, Xavier Pratt, Marcel Kampman.
