The Ontario club showed resolve to twice equalize, a man down and away to the reigning champions.
After a scoreless opening 45 minutes, Dom Dwyer struck early in the second half to tie the league lead for goals with nine. Wide open down the left flank, Sal Zizzo had time to pick Dwywer's diagonal run across the top of the box, and the Englishman threaded his shot into the far corner with his first touch to put the home side up 1-0.
Toronto's problems were compounded in the 63rd minute, when captain Steven Caldwell was shown a straight red card after connecting his studs with Antonio Dovale's thigh.
Despite going a man down, TFC equalized soon after. Jermain Defoe's penetrating run was chased down, but as the forward fell, he pushed the ball ahead to countryman Luke Moore, who finished from just inside the penalty area to make it 1-1.
KC reclaimed the advantage in the 84th minute. Igor Juliao flicked the ball past Doneil Henry in the box but went to the ground after colliding with the defender. Awarded a spot kick, Dwyer stepped up and took the lead in the Golden Boot race.
But TFC wouldn't be denied its positive result. In stoppage time, Bradley Orr beat Eric Kronberg to a Nick Hagglund cross and pushed a header into the net.
Sporting's record is now 5-4-3 on the season. Winless in their last three games, the one-leading Sporks have fallen to third place. TFC takes sixth place with its 4-4-1 performance so far this year.