Adam Kwasnik set the Mariners on course for the A-League grand final with the opening goal in the second leg of the major semi-final, but the Central Coast striker came within a hair's breadth of being rubbed out for the decider.

Kwasnik scored in the 37th minute after his speculative shot from the top of the box took a massive deflection off Jets defender Tarek Elrich.

It was a piece of good luck for Kwasnik and the Mariners, but arguably not the most fortunate moment of the game for the Central Coast striker.

That perhaps came early in the second half when the forward - already on a yellow card from the first leg - brought down Adam Griffiths.

Referee Ben Williams ran over to Kwasnik, but gave him only a dressing down - saving the 24-year-old from joining Sydney FC's Mark Milligan and Adelaide's Matthew Kemp as players banned from the grand final.

"I just pleaded with him that I was going for the ball, and basically he let me off and thank god for that," Kwasnik said after the match before being told by coach Lawrie McKinna to "stop smiling".

The Jets also benefited from a generous Williams.

Earlier in the first half, the referee appeared to reach into his pocket after a rash challenge from Matt Thompson on Nigel Boogaard, only to change his mind - saving the defender from a suspension in next Sunday's preliminary final against Queensland Roar.

Another flashpoint came late in the first half when Williams pulled out a card after a challenge on the edge of his box from Mariners goalkeeper Danny Vukovic on Joel Griffiths.

Fortunately it was just a yellow - and a harsh one at that given Griffiths had taken a blatant dive that should have instead seen the Jets star booked.

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