SYDNEY has lost yet another NEAFL Grand Final despite its opponent being caught with 19 players on the field, while the winner of South Australia's Australian rules preliminary final had an extra man on the field during an incredible comeback victory.

The SANFL hierarchy was holding an emergency meeting on Sunday night about the rule breach, which could result in North Adelaide's win against the Woodville-West Torrens Eagles being overturned.

North defeated the Eagles in Sunday's preliminary final at Adelaide Oval by five points, but they kicked 1.2 while having an extra player during a five-minute span in the last quarter.

The extra player was on field amid an extraordinary North comeback after they trailed by 47 points in the third quarter.

Eagles officials are understood to have complained to a reserve umpire and interchange stewards about North's extra player, a breach that could be penalised by wiping their entire score.

But under SANFL rules, only a captain or acting captain can ask an on-field umpire for a head count of players to officially determine an extra-man breach, which didn't happen.

Eagles chiefs were seeking legal advice on Sunday night.

"SANFL can confirm ... there were 19 North Adelaide players on the field at the commencement of the fourth quarter," the league said in a statement.

"SANFL is currently considering this matter and will provide a further statement as soon as possible."

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In the NEAFL drama, a minute into the last quarter the Swans trailed Southport by 60 points – 12.4 (76) to just 2.4 (16) – before extraordinary circumstances suddenly seemed to flip the flag decider on its head.

The umpires called the two teams together for a player count, where it was found the Sharks had an extra man on the field.

The home crowd at Southport's Fankhauser Reserve was stunned into silence at the prospect of the Sharks' entire score being wiped, which would have turned their 10-goal lead into a 16-point deficit. 

Confusion reigned as NEAFL officials consulted the rules, but the game went on, and the intensity of the contest lifted appreciably as the Swans suddenly got a sniff of a premiership and Southport attacked like a team possessed into a strong breeze.

Adding further panic into the Southport camp, the Swans immediately goaled with the wind through skipper Colin O'Riordan.

It took 25 minutes – until the dying stages of the contest – for word to filter out that the NEAFL had ruled that Southport's total would stand, in keeping with NEAFL and AFL by-laws.

In the end Southport claimed its first NEAFL premiership, prevailing by 55 points – 14.6 (90) to 5.5 (35). 

The NEAFL released a statement on Sunday night, clarifying the process followed during the game.

"During the 20 seconds in the final quarter when Southport had an extra player on the field, neither team scored any points," the statement read.

"After consultation with both clubs and ongoing discussion during the quarter, it was determined that the scores would remain as is.

"The decision was made in accordance with NEAFL rule 5.16.a.e: Where a player does not enter the playing field in accordance with these Rules, the Match Manager and/or field umpire(s) must report the circumstances to the AFL. Time and scores at the time of the breach are to be recorded. The AFL may determine the matter by way of fine, reversal of Match result or other sanction as it deems appropriate.

"In line with this rule, the NEAFL determined that the breach had no material impact on the outcome of the game and the score should stand."

The Swans reserves, coached by club great Tadhg Kennelly, are still yet to win a NEAFL flag, having lost five Grand Finals in six seasons.

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Their heavy defeat on Sunday was the latest disappointment in a tale of woe that has included narrow Grand Final losses in 2013 (eight points), 2014 (two points), 2016 (four points) and last year (three points). 

Kicking against a strong breeze in the first quarter, Sydney was immediately on the back foot when it conceded two goals in the opening minutes, and the first three goals of the game, before regaining composure to trail by 11 points early in the second term. 

However, that was all the resistance the Swans could muster, apart from their brief injection of adrenaline in the frantic final term.

Swans midfielder James Rose was superb in a side that was so comprehensively beaten, amassing 38 possessions, 15 clearances, seven tackles and the goal of the day – a brilliant snap from the boundary in the last quarter. 

Jordan Dawson kicked the Swans’ first two goals and three for the match and laid 10 tackles, while rookie-listed Irishman O’Riordan gathered 27 possessions, and ruckman Darcy Cameron was solid with 19 touches and eight marks. 

Swans rookie Jake Brown appeared to be knocked out in the third quarter after copping an accidental elbow.

Among the most prominent Sharks were Tyler Roos (35 possessions across half-back) – the son of Swans premiership coach Paul Roos – and former Gold Coast player Andrew Boston, the captain of Southport.