The star recruit is yet to force his way into a well-drilled back-line and there is no indication that will change for this week's match away to Melbourne Heart
Spiranovic was a high-profile signing for the club in the off-season but has yet to be sighted in a Wanderers jersey in the A-League.
The 25-year-old has been improving his match fitness in the club's National Youth League side and has been included as part of an extended squad for Friday night's clash with Melbourne Heart.
But Popovic made no guarantees the highly-rated defender would finally make his Wanderers debut.
"When he will be back? That's up to us to decide when he'll play but he'll certainly play a part this year," Popovic said ahead of the clash at AAMI Park.
"He's been available for a few weeks; it's just our choice has been not to put him in the team.
"It will be unfair to keep singling Matty out because there are a lot of players that are here in the squad that are trying to play and get into that first eleven.
"Matty's just one of them."
There is the option of playing Spiranovic in a defensive midfield role in front of in-form central defenders Michael Beauchamp and Nikolai Topor-Stanley but Popovic said that's unlikely.
"You always look for all the options as a coach, and he's a very good player so you don't discount anything," the Wanderers boss said.
"But that's something we're not looking at at the moment."
You can't blame Popovic for his reluctance to make too many changes to his side, with the Wanderers unbeaten from their four matches this season.
They take on a Heart team who they have beaten on all three occasions they have played, with John Aloisi's side languishing on the bottom of the table with no wins this season.
"I don't think their position reflects how well they've been playing," Wanderers attacker Mark Bridge said of the Heart.
"They've been unfortunate a few games. They were up 2-0 against Central Coast and finished with a draw, and even against Brisbane on the weekend they were unlucky.
"Johnny (Aloisi) and (Hayden Foxe) have got them playing very well and I think they are going to be a dangerous team."
The Wanderers will again be without influential winger Youssouf Hersi, with Brendon Santalab expected to continue as his replacement on the right.
"He's getting better. He was quite well behind in terms of his fitness when he got to the club, and he had an unfortunate illness where he missed 10 days and was bed-ridden for 10 days," Popovic said of Santalab.
"That was just before the start of the year, and you can now see that he's starting to get stronger, and we know that he'll get better and better."