Sporting Kansas City kicked off its 2012 0 win over D.C. United at RFK Stadium on Saturday.
Sapong came on as a second-half substitute and marked the occasion with the game-winning strike deep into stoppage time as the former James Madison University standout ghosted into the box unmarked to nod home a corner kick delivered by Graham Zusi.
Sporting made a habit of deciding matches late in the game throughout the 2011 season, and the 2012 season opener was no different as Sapong's strike in the dying minutes capped off a night of domination for the visitors in the nation's capital.
Kei Kamara came close to opening the scoring in the 36th minute when he received a pass from Zusi on the counter attack. The Sporting striker chipped in a cheeky effort from the corner of the box, but it sailed just wide of the goal frame.
United responded two minutes later with a close scoring chance of their own. Chris Pontius collected possession and cut inside before unleashing a shot from the top of the box, but his effort trickled inches wide of the post.
The closest chance of the first half came just prior to the break when Roger Espinoza sent a pinpoint cross to the edge of the six-yard box. Kamara met the delivery with a header, but his effort was kicked to safety by United goalkeeper Bill Hamid.
The second half began with a series of half-chances for both clubs, though neither team truly threatened to get in front.
Zusi demonstrated his danger from distance as he lashed a rocket toward goal in the 72nd minute. Hamid made a sprawling save and spilled the ball, but he was able to quickly smother it to deny Sporting the chance to stuff home the rebound.
Second-half substitute Maicon Santos answered Zusi's long-range effort with one of his own, striking a free kick in the 84th minute that dipped right in front of Jimmy Nielsen. The Sporting stopper was equal to the challenge though, as he swallowed up the shot with little trouble.
D.C. thought it had earned a draw for its defensive efforts, but Sapong spoiled the party by popping up with a late winner to deny United three points at home.
Sporting will head home to Livestrong Sporting Park for its next league fixture as it will host the New England Revolution on March 17.
D.C. United, meanwhile, will return to action on March 18 with a tough encounter at The Home Depot Center against the Los Angeles Galaxy, who were not beaten at home during the regular season in 2011.