Traore picked up his fifth yellow card of the campaign in a 5-0 loss away to Wellington Phoenix last time out and will serve a one-match ban this weekend, with Dylan Murnane to replace him at Etihad Stadium on Sunday.
Contreras meanwhile limped off the training field early in the session on Friday morning with a possible quadriceps injury.
"There was no indication of anything before training," Victory coach Kevin Muscat said.
"For him to go in would suggest he felt something but hopefully it's nothing too serious."
The 1-1 draw with Western Sydney Wanderers on December 28 was the last time Victory were able to name a back four unchanged from their previous fixture. In the subsequent four games, they have lost twice and drawn once, conceding 10 goals in the process.
Scott Galloway trained with the first team and is likely to start at right-back ahead of Jason Geria, while Nick Ansell is in line to partner Adrian Leijer if Contreras is ruled out.
The Chilean has endured a difficult time since joining Victory, with his value questioned after some shaky performances and disciplinary issues.
The 35-year-old is highly unlikely to remain with the club beyond the end of this season following the news Besart Berisha will leave Brisbane Roar and join Victory as the Melbourne side's international marquee player on a two-year deal.
Muscat meanwhile welcomed the announcement that English Premier League giants Manchester City have purchased a controlling stake in local rivals Melbourne Heart, but does not anticipate a major shift in his own club's approach as a consequence.
"It's a massive step in the right direction for the competition that someone of Man City's calibre decided to invest in the A-League," he said.
"From our perspective we just carry on improving our football club steadily and not worry too much about what's happening across the road."
