After DC United's narrow win over Toronto on Saturday, Sporting KC had to beat the lowly Fire to return to the summit but they were forced to settle for a share of the spoils at Sporting Park.
Sporting KC forward Dominic Dwyer opened the scoring in the 33rd minute, only for Chicago star Mike Magee to level proceedings seven minutes later in Kansas City.
Peter Vermes' men are second in the standings on 26 points after 17 rounds, two adrift of DC United.
The Fire, who are without a league win in six games, are second-bottom with 16 points from as many matches.
Sporting KC went into the match on the back of back-to-back triumphs against Houston Dynamo and the Portland Timbers, but it was the visitors that should have taken an early lead.
After Kevin Ellis surrendered possession to Magee in the second minute, the former Los Angeles Galaxy man was presented with a one-on-one situation with Sporting KC goalkeeper Eric Kronberg but he was too slow to unleash his shot on target.
The Fire continued to have the better chances and Magee was unfortunate not to have put the visiting side ahead after his 31st-minute effort hit the right post.
Chicago were made to pay two minutes later, when England's Dwyer dispossessed Patrick Ianni just outside the penalty area and showed terrific composure to place the ball beyond goalkeeper Sean Johnson - his 12th goal of the season.
Sporting KC's joy was short-lived, however, as Magee found space in between the home side's defence before finding the back of the net after being played through by Brazilian team-mate Alex.
