Orlando City (3-2-2, 11 points) posted their first win in three matches (1-1-1).
It's the first loss of the season for the Fire (2-1-3, 9 points), who have been shut out in two straight matches.
Chicago played more than half of the match down a man after midfielder Brian Gutierrez was shown his second yellow card in the 43rd minute.
The Lions had the better of the opportunities in the first half, although only four of their 10 shots were on goal.
In the sixth minute, Mauricio Pereyra broke into the box but was stopped by goalkeeper Gabriel Slonina. Four minutes later, Alexandre Pato came close with a shot from the top of the box but the Brazilian striker's attempt rolled just wide.
The Fire had one of their best chances of the opening half in the 15th minute. Gutierrez tried to finish off a cross while alone at the top of the area but was denied by goalkeeper Pedro Gallese.
From then on, Orlando spent considerable time in the attacking third. In the 20th minute, Pato was stopped by Slonina off a feed from Ruan, and his shot from above the box sailed over the crossbar three minutes later.
Orlando finally connected in the 59th minute off a free kick. Torres kicked the ball to Pato, who headed it to Kara, who headed it into the net to open the scoring. It was Orlando's first goal off a set piece this season.
The home side had several chances to add to its lead but continued to struggle to hit the target, with shots rolling wide or over the net.