Glory's unbeaten run continues at the expense of United, who were outplayed and outclassed by Ian Ferguson's in-form men.
Perth Glory moved a step closer to guaranteeing their first A-League home final and continued Gold Coast United's tough run with a 4-0 thrashing at nib Stadium on Monday.
The Glory went ahead after 18 minutes through Steven McGarry's third goal in his past five games and would have had the three points wrapped up by half-time if not for their wasteful finishing.
But Liam Miller scored eight minutes after the break, before Travis Dodd added another and Adama Traore put the ball into his own net to ensure Perth capitalised on a dominant performance.
Their unbeaten streak now reaches to eight games - their longest run without a loss in the A-League.
Ian Ferguson's side moved four points clear in fourth spot with the win and only needs to hold onto that position over the last seven rounds to earn its first home final in the seven seasons of the A-League.
Gold Coast, who were poor across the park in a hapless display in their heaviest loss of the season, are now winless in their last seven games and are five points behind ninth-placed Adelaide.
Under-strength United side, without the likes of Dylan Macallister, Tahj Minniecon, and James Brown, struggled to cope with a first-half Glory onslaught in front of 7681 fans.
Shortly after Jacob Burns' shot cannoned off the crossbar, the hosts went ahead when Steve Pantelidis flicked on a corner to an unmarked McGarry at the back post and the in-form midfielder headed into the top corner.
Gold Coast's best chance of the half came when Ante Rozic drifted unmarked from a free-kick after 30 minutes and headed wide from six yards.
Shane Smeltz then endured a horrible spell when he missed three one-on-one chances in quick succession, sending one effort wide, hitting the post with the second and having the third saved.
Gold Coast's display after the break did not improve and they were made to pay when they dealt with a Travis Dodd cross poorly and Liam Miller tapped in from close range.
Jonas Salley nearly got United back in the game but his header was cleared off the line, and Perth wrapped up the win in the 67th minute when Dodd beat his man at the near post off Mile Sterjovski's corner and headed home.
And a bad match got even worse for Gold Coast in the final minutes when Traore woefully miscued an attempted headed clearance and scored an own goal.
The Glory's third-straight win saw them retain the Iron Ore Cup.