Reds rise into the top six
Marcelo Carrusca's fortuitous fourth-minute goal had the Reds firing early and it proved enough for Josep Gombau's charges, who moved above Perth Glory, the Newcastle Jets, Sydney FC and Wellington Phoenix on the table in one hit.
The victory, fresh off last week's stunning 2-1 triumph over the league-leading Brisbane Roar at Suncorp Stadium, gave Adelaide successive wins for the first time in more than 12 months, against the competition's top two sides, no less.
The Wanderers, playing their third game in eight days, needed to be switched on early, but instead endured an absolute nightmare of a start.
Carrusca, making his return from injury, pounced on the back of a goal-line scrimmage, threading a sharp goal from a tight angle after Bruce Djite had stolen the ball out of diving Western Sydney goalkeeper Ante Covic's hands.
Television replays showed the Wanderers were desperately unlucky, the ball appearing to be just out of bounds in the lead-up to Carrusca's strike.
Rubbing further salt into the Wanderers' wounds, Aaron Mooy copped a yellow card for his challenge on Osama Malik and Adam D'Apuzzo was booked after felling Djite, both inside the first seven minutes.
Carrusca was in the thick of the action again when he played fellow Argentine Jeronimo Neumann through beautifully, Jeronimo's shot on a bursting right-flank run veering just to the left as the hosts continued their early domination.
The shell-shocked Wanderers finally settled and almost equalised on 20 minutes when a sliding Labinot Haliti came agonisingly close to getting on the end of an expert Shinji Ono pass.
One out, Jeronimo had a close shave at the other end, unable to capitalise on the burst and hurting his right knee in the process.
The star striker was tended to by the Reds medical staff before coming back onto the pitch, but Michael Zullo was not so fortunate, hurting his right leg in a collision and limping out of the contest in the 34th minute.
The Wanderers captured the impetus late in the half and almost levelled proceedings in the most spectacular fashion when the classy Ono leapt for a bicycle kick, his reverse effort landing on the roof of the net.
Western Sydney worried United but the home side's defence was up to the task, repelling numerous attacks to maintain their 1-0 lead at half-time.
Reds custodian Eugene Galekovic almost fell over his feet in the 46th minute but recovered to repel a sequence of Wanderers corners.
Boom recruit Ryan Griffiths, who signed with Adelaide earlier this month, entered the fray off the bench in the 60th minute and almost created a goal with his first touch with a cutting cross inside the box.
Djite's long-range missile in the 69th minute soared wide of the mark before Jeronimo's 89th-minute rifle was magnificently saved by Covic.
United, having withstood the Wanderers' best punches, recaptured their earlier advantage late and confirmed their new-found standing as a championship dark horse.
Adelaide United 1 (Carrusca 4') def Western Sydney Wanderers 0
Crowd: 11,356 at Coopers Stadium