It was the second match-winning performance he's produced since returning from a torn ACL in August, but he believes he's nowhere near his best.
"No, no, no, I'm not 100 percent yet," Mihailovic told MLSsoccer.com. "Once I can go a full-90 without asking for water from the sidelines then I'll be 100 percent. My doctor told me 12-14 months until I'm fully 100 percent. By next season, especially going through a full preseason, I'll be 100 percent."
The 19-year-old Homegrown Player broke into the first team last season, making his senior debut and growing into a key member of the team. He had started the final four matches of the Fire's season, as well as their Knockout Round match against the New York Red Bulls in the playoffs.
Then he went in for a slide tackle and his knee got stuck in the turf, devastatingly resulting in a torn ACL.
"It was really painful," Mihailovic said, referring more to emotional anguish than physical. "After progressing through the season, earning my minutes and getting a run of games that I started. Especially in a playoff game, to go down like that is something you never want to think about. I look at it now as something that really helped me. It changed the way I play, changed the way I view the game."
Rehabilitation for the injury isn't easy. Behind closed doors, Mihailovic would wake up at 6 am and begin work at 7:30 am until 3 pm. Every day, for the better part of a year.
"It's a mental challenge more than a physical challenge," Mihailovic said. "You see all your teammates going onto the field, smiling, enjoying the game, and you can't be there yet. It's really painful."
The rehab itself, as well as being forced to watch the game rather than participate on the field, has helped sharpen his mental side of the game.
"When you're healthy, you never think about jogging without pain. You never think about the little things," Mihailovic said. "After I tore my ACL, I had to learn how to walk again, how to jog again, how to walk up the stairs. Something that was so mentally challenging, you take the little things now like a big thing."
Mihailovic later added: "Watching the game with a different perspective, it's like you're kind of coaching, not playing. That shaped my mentality towards the game."
Mihailovic made his return on Aug. 18, a time he would have hoped the team would be focusing on the playoffs. Instead, 2018 went wrong for Chicago and the team has been eliminated from playoff contention.
"We're professionals, we owe it to ourselves, the city and the club that we don't give up no matter what," Mihailovic said. "I'm trying to look at it as how high can we make it in the standings? It's one thing to be dead last and just quit, worry about next season. But if we win the next three games, we can probably be two spots behind the playoffs and it'll be a whole different scenario. It's 'we were almost there' and not 'it's a terrible season.'"
"That's the first time I'm hearing that. Oh, Stef. That's interesting," Mihailovic paused to laugh. "All jokes aside, all 11 players have a role on the team. My role now, versus last year, has completely changed. ... I don't look at myself as some young player who has a lot of talent who needs to learn. Right now, I look at myself as a key starter that can contribute and be a leader as well.
"That might have been what Stef meant. I can't really score those kinds of goals every week, but I'll try my best!"