The former U.S. international striker has endured a tough season, but now has scored three goals in two matches.
The visitors took the lead thanks to some incisive passing and lax TFC marking. Graham Zusi picked out Dom Dwyer in the box with a long cross-field ball, and the forward headed across the face of goal to a wide-open Sapong, who was left with a simple header to score.
The home side got back level after some poor play from SKC's back line. Jimmy Nielsen's pass out of the back eluded Aurélien Collin, and Alvaro Rey picked up the turnover. The Spaniard then found Darel Russell, who drilled a low shot home from the top of the box.
Sapong grabbed his second a few minutes after the break. Again, it was an unmarked header in the box, as the forward darted in front of Mark Bloom to head home a great long cross from Chance Myers.
TFC's mission was made more difficult with just minutes to play, when Steven Caldwell was given a straight red for an ugly raised-foot challenge on Josh Gardner.