The Dynamo won the opening leg Sunday behind goals from Adam Moffat and Will Bruin, and then did enough on defense -- just barely -- to advance to its second straight conference title game.
Houston defeated Sporting KC last year to reach the MLS Cup finals.
The Dynamo will open the conference finals on the road against D.C. United or the New York Red Bulls in another two-game, aggregate goal series scheduled to begin Sunday. United and the Red Bulls played to a draw in their first game, while their return game Wednesday night was postponed due to the Nor'Easter dropping snow in the New York area. The second leg of that series will be played Thursday, with the opening leg of the conference finals pushed back a day as well.
Sinovic provided a jolt through a crowd of 20,894, the second-largest ever to see an MLS game at Livestrong Sporting Park, when his diving header off a cross from Graham Zusi found the back of a wide open net to give Sporting KC the lead in the 64th minute.
Kei Kamara set the play up with an impressive individual run into the box.
The regular-season conference champions spent the next 30 minutes desperately trying to find the second goal that would force overtime, getting several good looks -- just as they had all game.
Every time, though, Houston's physical back line would make a play to knock the ball away from danger, or goalkeeper Tally Hall would leap forward to snatch a through ball and spoil an attack.
The outcome was never assured for Houston, which was outscored by at least two goals in the second half three times this season, until 4 minutes of stoppage time expired.
There was no massive celebration, though, just exhaustion on the part of the Dynamo.
They shook hands with Sporting KC players and clapped each other on the back, but it was clear that the pressure of spending 90-plus minutes on their heels had sapped them.
The Dynamo squeaked into the playoffs as the fifth seed in the Eastern Conference, but beat fourth-seeded Chicago in the knockout round, and then continued its dominance of Sporting KC with a 2-0 win in the first match of the two-leg conference semifinals.
The result allowed Houston to adhere to coach Dominic Kinnear's style by sinking back on defense and muddying up the middle of the field, forcing Sporting KC to swing passes wide on the wing and then force looping shots into the penalty area, where its size could knock them away.
That's what happened in the eighth minute, when C.J. Sapong drew a foul and Zusi uncorked a free kick from 25 yards that Kamara managed to get his head on but send just wide of the goal.
It happened again in the 26th minute, when Kamara's shot was deflected away, and early in the second half, when Zusi's sent a free kick arcing into the box that was knocked back out.
Sporting KC nearly had the series equalizer in the 73rd minute, when C.J. Sapong beat the Houston defender to a pass from Kamara, and the forward chipped the ball just over Hall, who was late in trying to secure it in front of the next. The ball just cleared the crossbar.
Matt Besler another chance in the 85th minute, when his right-footed shot was high and wide.
Houston held on from there to end a successful season for Sporting KC.
The recently rebranded club, playing in its still-new state-of-the-art stadium, captured Kansas City's imagination. Not only did it repeat as regular-season conference champions for the first time in club history, it also won the U.S. Open Cup for only the second time.
It all ended in a matchup of what are fast becoming bitter conference rivals.