The reigning cup winners proved too strong for Paul Reid's NPL NSW club Rockdale City Suns, triumphing 4-2.

The Suns had gone ahead early through Gaitatzis, but Sydney responded emphatically with the next four goals at Illinden Sports Centre.

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Adelaide's new signings Mirko Boland and Craig Goodwin were both on the scoresheet as the Reds eased past Central Coast 3-0 at Marden Sports Complex.

The Mariners, who were remarkably playing their first game in pre-season, bow out in the Round of 32 for the fourth straight season.

Elsewhere, NPL Queensland club Cairns FC were too good for NPL WA club Armadale 4-0, while Heidelberg United made the last 16 again with a 2-1 win over Charlestown City Blues.

Rockdale City 2 (Gaitatzis 6', Alameddine 76') Sydney FC 4 (De Silva 30', Warland 48', Brosque 51', 64'), Illinden Sports Centre

Ex-Juventus trialist Harris Gaitatzis lobbed home an early goal for Rockdale which left Sydney stunned, but new recruit Daniel De Silva stepped up with a fine volleyed strike on the half hour mark.

Ben Warland put Sydney ahead before veteran skipper Alex Brosque hit a brace to ease any concerns. Toufic Alameddine grabbed a late consolation for the Suns.

Heidelberg United 2 (Davison og 1', Ellis 13') Charlestown City Blues 1 (Ott 82'), Olympic Village

The NPL Victorian club raced to an early two-goal lead to set up the victory. Daniel Ott fired in a superb strike from outside the box for a consolation for the NPL Northern NSW side.

Adelaide United 3 (Elsey 12', Boland 19', Goodwin 53') Central Coast Mariners 0, Marden Sports Complex

Jordan Elsey and Boland put the Reds in a commanding position after 20 minutes before Goodwin settled the contest after half-time with an exquisite free-kick.

Isaías’ set-piece was initially flicked on by Apostolos Stamatelopoulos but Elsey was alert at the back post to volley home. Seven minutes later, Goodwin swung in a deep cross from the right wing but Jake McGing’s header back across the face of goal fell to Boland who instinctively executed an overhead kick on 19 minutes. 

The second-half saw Adelaide again quickly get on the front foot and Goodwin capped off the win with a perfectly executed free-kick involving Isaías in the 53rd minute.

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Cairns FC 4 (Carroll 51', Taylor 68', Koppen 79', O'Hare 90') Armadale 0, Barlow Park

The Far North Queensland club raced away with this contest after a goalless first half. The Perth club's hopes were severely hampered by a tough 19th minute red card to defender Beau Rahim who was adjudged to be the last man upon a foul.

Jamie Carroll put Cairns ahead and set up the second, before a sweet late volley from Crios O'Hare put the icing on the cake.