Playing their first season of NSW National Premier Leagues first division, North Shore were expected to struggle this year.

The side sent a message to the competition last week when they drew with 2019 champions APIA Leichhardt but it was a message the Wolves did not heed, the reigning premiers stunned by the Mariners at Albert Butler Oval.

The Wolves started fast, Thomas James scoring in just the 12^th minute and Littler, who stood in as captain for the injured James Stojcevski, conceded his side switched off from that point.

"I think we may have underestimated them a bit," Littler said. "We went up early, then the wheels fell off. We took the foot off the accelerator and then fell to pieces.

"We created enough attacking chances that we probably could've won. At the end of the day that frustration comes out and we don't score goals."

James' goal acted as a catalyst for North Shore, the visitors working their way into the match.

That saw the Mariners hold the territorial advantage throughout the final 15 minutes of the first half.

Eventually the weight of possession turned into an attacking opportunity and it was Panny Nikas who levelled the scores in the 42nd minute.

The second half was a physical affair, both teams testing the referee's limits as they attempted to break the deadlock.

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Tensions threatened to boil over on a number of occasions, with the Wolves growing increasingly frustrated as the pressure grew.

Wollongong slowly regained the upper hand in proceedings, only for the Mariners to hit the front in the blink of an eye.

North Shore turned defence into attack, Emmanuel Peters getting in behind the Wolves defence to score his team's second goal in the 72^nd minute.

James appeared to have saved the Wolves blushes when he landed an 80^th-minute penalty, only for the hosts to switch off defensively 11 minutes later, Mitch Smith pouncing on a loose ball in the box to score his team's third.

The 91^st-minute goal proved to be the match winner and Littler said it was disappointing to concede two poor second-half goals.

"It's always terrible to concede goals. We conceded 12 all last year, we're a third of the way there already this year. We need to pick it up next week."

The loss provided a rare example of a Luke Wilkshire-coached Wolves side being out-enthused by their opponents, the Mariners fighting for the three points right until the end.

That, for Wilkshire, was the most disappointing aspect of the performance and he said North Shore earned the three points.

"It's disappointing," Wilkshire said. "At home, it's a very disappointing result.

"We didn't defend as well as we can do, we conceded some sloppy goals. I think they wanted it more and in the end we got what we deserved, and that was nothing.

"When you look at goals, there's always a combination of errors leading up to it. They just wanted it more than us. Their hunger and their desire was greater than ours today and that's why they got what they got."

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