Melbourne Victory became the first A-League side to win three Premiers’ Plates, defeating Central Coast Mariners 3-1 on the final day of the 2014/15 regular season. Earlier, Sydney FC’s 2-1 win over Wellington ensured the race for the Plate would come down to the last day, with Victory needing to avoid a loss of more than six goals, but such an unlikely course of events was never on the cards.

The last-round results confirmed Adelaide and Wellington as hosts for week one of the finals series. On Friday, Brisbane will travel to play Josep Gombau’s Adelaide United. The Phoenix host Melbourne City in New Zealand on Sunday. Winners from week one will play Victory and Sydney FC in week two for a place in the A-League grand final.

After a trophyless six years, Victory finished the home-and-away season as top dogs, first-half goals to Daniel Georgievski and Archie Thompson setting their premiership party in motion on Sunday. Eddy Bosnar’s deflected free-kick reduced the Mariners’ deficit, but Victory went on to celebrate with a half of champagne football, capped by an exceptional third goal to Besart Berisha, which encapsulated their season perfectly – perseverance, teamwork and stunning attacking football.

Thompson chased down a loose ball on the left wing, crossing to Gui Finkler via a neat Kosta Barbarouses touch. The Brazilian flicked the ball up for Mark Milligan, who laid off for Berisha to lash home his first goal at AAMI Park for Victory. It was a sweet moment for premiership coach Kevin Muscat, who celebrated richly with the 22,285-strong crowd.

In truth, there was only ever an infinitesimal chance of Victory throwing away the Premier’s Plate to Sydney FC on the final day. The Mariners, confirmed in eighth place and with nothing to play for, needed a seven-goal win to deny Victory the premier’s plate.

They began as if their holidays had already arrived and were behind after half an hour. Georgievski’s neat chip from his own rampaging run gave Victory a lead. Three minutes later, Thompson’s glancing header from Finkler’s corner beat Matthew Nash in the Mariners goal. On the stroke of half-time, Bosnar’s 30-metre rocket found the net via the Victory wall.

But after half-time it was all Victory, who deserved their win and premiership. The joyous crowd chanted “Super Kevin Muscat” and there was even acknowledgement for former coach Ange Postecoglou. The Socceroos boss was appointed as Victory coach three years ago to the day, and enjoyed a huge applause when showed on the big screen.

Barbarouses was agonisingly close to adding a fourth with four minutes remaining but his volley was centimetres wide.

Bernie Ibini scored a fantastic solo goal to open the scoring for Sydney FC. Photograph: Ross Setford/AAPIMAGE

Sydney FC secured second spot on the ladder with a controlled 2-1 win over Wellington Phoenix at Westpac Stadium earlier on Sunday. The victory secures a week off for the Sky Blues before they host a home semi-final, leaving the Phoenix in fourth place to host an elimination play-off against Melbourne City next weekend.

The win also continued Sydney’s season-long unbeaten run away from home and was set up by clinical first half goals to Bernie Ibini and former home-town hero Shane Smeltz.

Wellington fought back in the second spell with a goal from Michael Boxall less than a minute after the restart. But despite creating numerous chances, Wellington couldn’t find the equaliser.

Sydney were unrattled by the late withdrawal of golden boot leader Marc Janko through injury, with the pace of Ibini and Chris Naumoff dominating the midfield. Skipper Alex Brosque and Smeltz also impressed and provided plenty of options in the front third.

The Phoenix again spurned a gilt-edged early chance when referee Strebre Delovski pointed to the spot after Ibini chopped down Michael McGlinchey after just 10 minutes. Roly Bonevacia stepped up to the spot but skewed his shot wide, with Ibini making Wellington pay three minutes later.

Set loose on a storming run down the left, the pacy striker turned Boxall inside out before slamming the ball home.

Former Phoenix favourite Smeltz doubled Sydney’s lead after 30 minutes, stepping up to the spot and coolly converting a penalty after Albert Reira brought down Naumoff.

Wellington halved the deficit barely a minute into the second half, working a smooth variation to score for the first time all season off a corner. The decision to go short worked a treat with Burns hauling back a cross for Boxall’s poised finish which galvanised the crowd of 13,248 back into full voice.

Brosque almost silenced them in the 63rd minute when he broke clear to confront Lewis Italiano one-on-one. But the stand-in keeper stood strong and made a point-blank save.

Wellington pushed hard right to the final whistle but couldn’t repeat the heroics of the previous week’s 95th-minute winner against Central Coast Mariners.