Stunning first-half strikes from Kirsty Fenton and Fiona Worts sent Sydney on their way in front of a record 11,471 fans on Saturday night.
The crowd figure was an ALW record for a standalone game, beating the 9519 at Sydney's 4-0 win over Western United in last season's grand final.
But Sydney's opening-round win came at a major cost, with Tobin seriously injuring her right knee during a collision with an opponent in the 50th minute.
Tobin was later seen on the bench with her knee heavily iced and crutches next to her.
Scans will determine whether she has suffered a dreaded ACL tear.
Saturday's result marked the eighth consecutive game in which the Wanderers have failed to score against the Sky Blues.
Star Matilda Cortnee Vine was a constant headache for Western Sydney in the first half, going close to scoring on numerous occasions and also setting up her teammates for golden chances.
But it was Fenton who got the ball rolling, with the 20-year-old unleashing a powerful volley from outside the box that goalkeeper Kaylie Collins couldn't keep out despite getting a palm to it.
It was 2-0 in the 36th minute when a running Worts chipped the bouncing ball past the goalkeeper after a pinpoint assist from Princess Ibini-Isei.
The Wanderers created plenty of good chances in the second half, but Sky Blues goalkeeper Jada Mathyssen-Whyman was able to pull off a series of stunning saves.
Perth Glory started their campaign with an impressive 2-0 win over last season's runners-up Western United in Perth.
Susan Phonsongkham opened the scoring in the 49th minute with a low curling strike through traffic.
New Zealand international Grace Jale secured the points with a 79th-minute wonder strike from the edge of the box.
Earlier, Central Coast's ALW return ended in a 1-0 loss to Newcastle in an F3 derby that featured a rare double send-off.
The Mariners, who exited the competition in 2009 due to financial constraints, had a vocal home crowd of 5735 cheer them on in their return.
Tempers boiled over in the 78th minute as players from both teams came together, resulting in Jets defender Alexandra Huynh and the Mariners' English recruit Faye Bryson being sent off for their involvement in a push and shove.
Both players were already on yellow cards, and they were made to pay dearly for the feisty display.
The incident seemed to help Newcastle, who scored three minutes later when former Victory striker Melina Ayres jumped high to head home a powerful winner.
It was a deserved victory for the Jets who had 16 shots to five, including seven shots to one on target.
The Mariners lost goalkeeper Sarah Langman to injury in the lead-up to the match, with Central Coast signing Courtney Newbon as a last-minute replacement and thrusting her straight into the starting XI.
15°C