Marcelo Carrusca opened the scoring for United before Tomi Juric struck twice against his former side to hand the Wanderers their second win of the season
The Reds looked on track for an upset away win when the returning Marcelo Carrusca poked home Jeronimo Neumann's shot-turned-cross nine minutes into the second half.
But Juric, who spent the second half of last season at Adelaide, turned the game around with two wonderful goals much to the delight of the 16,279 fans at 'Wanderland'.
The young striker did it all himself to draw the sides level on the hour, beating Eugene Galekovic with a bullet strike from just outside the area, although the Reds were adamant Aaron Mooy had handled the ball in the build up.
Then with 10 minutes left the United defence switched off at a throw-in on the right, allowing Jerome Polenz to get a cross in, with Juric shrugging off Tarek Elrich to head home.
It was a just reward for the home side who, despite giving up most of the possession to the Reds, still managed to create the majority of scoring chances.
After starting the season with back-to-back draws, the Wanderers have now claimed two straight wins and are now temporarily on top of the league with the rest of the round's matches to be played over the weekend.
Adelaide's night didn't start well when they were forced to walk to the ground after their bus didn't show up at the team hotel.
And they were lucky not be caught stranded again inside the first minute, with only a smart save from Galekovic down low to his right keeping out Nikolai Topor-Stanley's goal-bound header.
Midway through the half, the home side then squandered a glorious double-chance to break the deadlock.
First Juric stung the palms of Galekovic with a dipping shot from just outside the box, before the rebound fell to Brendon Santalab but his sweetly-hit volley fizzed across the face of goal.
Former Wanderers defender Elrich was lucky not to be sent off soon after, when he cynically fouled Mark Bridge just minutes after picking up a yellow card for dissent.
The visitors' good fortune continued soon after when Iacopo La Rocca looked certain to score from Shinji Ono's cross, only to find the side-netting from close range with the goal gaping.
Adelaide's best chance came just before the break when Carrusca's free-kick found its way through to Sergio Cirio, but he didn't get enough purchase on his header which allowed Ante Covic to save.
It was the only bit of work the Wanderers keeper had to do in the first half but just nine minutes after the break he was picking the ball up out of the back of his net.
Neumann was given too much space just outside the box, with the Argentine's shot taking a slight deflection and falling perfectly into the path of Carrusca to pounce.
It took just six minutes for the home side to draw level, although there was a hint of controversy about it.
The Reds were irate, believing Mooy handled the ball as he won possession in his own half but referee Jared Gillett waved play-on.
And within a flash the Wanderers broke downfield with Juric cutting in from the left and hitting a rasping low drive from just outside the box which stunned Galekovic as it nestled in the bottom corner of the net.
With the huge home support behind them the Wanderers pushed hard for a winner but Mooy, Tahj Minniecon and Ono all squandered good chances in the space of a few minutes.
But their pressure eventually told as Juric was on hand to head home Polenz's cross to give the Wanderers their first win on their home turf this season.
Western Sydney Wanderers 2 (Juric 60, 80)
Adelaide United 1 (Carrusca 54)
Crowd: 16,279 at Pirtek Stadium