REDLANDS United have caused the biggest boilover in the FFA Cup’s short history, defeating A-League champions Adelaide 2-1 at Perry Park.

A night after fellow second-tier club Green Gully knocked out A-League battlers Central Coast, the NPL Queensland outfit upped the ante by beating the so-called best club team in Australia to advance to the last 16 of the Cup.

And it was the manner of the win that had the crowd of 1564 overcome with joy and emotion.

Adelaide dominated the contest, taking a deserved 1-0 lead in the 62nd minute through Ryan Kitto.

It seemed like it was going to be enough until a shocking error from the usually reliable Adelaide goalkeeper Eugene Galekovic gifted Redlands an expected equaliser in stoppage time.

Redlands players swarm Paul O'Brien after he netted the match winner. Source: Getty Images

Galekovic misjudged a bouncing through ball before a clumsy and unsuccessful attempt to grab it allowed Redlands attacker Michael Lee to sneak in and tap the ball into an empty net.

Worse was to follow for Adelaide in extra time.

Slack defending from Tarek Elrich and Dylan McGowan allowed Lee to deliver a dangerous low cross into the visitors’ penalty area in the 98th minute.

Substitute Tyler Bradley-Combe got a vital touch, helping the ball on its way to Paul O’Brien, who shot the ball past an exposed Galekovic.

As had been the case for almost the entire contest, Redlands – currently in sixth spot on the NPL Queensland ladder - then defended stoically to hold on for a famous victory.

“We fight for each other every tackle, every week and I genuinely think that’s why we won,” goalscorer Lee said.

lacopo La Rocca is taken from the field. Source: Getty Images

“We’ve all got each other’s back. That’s why I think we got over the line.”

Redlands coach Matt Chandler described it as an “amazing night” for Queensland football.

It was only the third time in Cup history that an A-League team had been beaten by a lower-tier club.

The already depleted Adelaide’s night was made worse by a potentially serious injury suffered by Iacopo La Rocca.

The Italian import was forced off the field inside the first 10 minutes when he came off second best in what seemed to be a clash of heads with Redlands defender Grant Brix.

La Rocca was later taken to hospital for scans on his cheek and eye socket.

Ryan Kitto of Adelaide and Grant Brix battle for possession. Source: Getty Images

Adelaide coach Guillermo Amor was devastated by the loss.

“Sometimes this can happen (but) it shouldn’t happen,” Amor said.

“We had the game, the victory until the last minute … I’m disappointed. It’s not good for us.

“Our target and objective was to win this Cup, but in one game, we’ve gone out.”

The other Queensland team in action tasted defeat, with Surfers Paradise Apollo losing 1-0 away to Canberra Olympic.

Cup holders Melbourne Victory beat Newcastle Jets 3-1, while Bonnyrigg White Eagles defeated Manly United 3-0 in an all NSW-affair.