The Roosters were tackled in front of the uprights, about 15 metres out from the Rabbitohs line when the game clock appeared to hit zero, yet the siren was not sounded, giving them the extra play in which they scored.
Five-eighth Dylan Walker played a starring role for the Rabbitohs, scoring two tries and four goals for a personal tally of 16 points.
The Rabbitohs opened the scoring in the fourth minute through second-rower Brad Croad who displayed good, hard, straight running close to the line to score. Walker converted to give the Rabbitohs an early six point lead.
Ten minutes later the Roosters scored their first four-pointer through winger Graeme Su'a Poe in the left corner.
The Roosters took the lead for the first time when replacement forward Jack Noble scored the first of three tries in the 23rd minute. The Rabbitohs were gifting the tricolours possession and field position with ill-discipline, leading to the points. Brendan Elliott converted to give the home side a 10-6 lead.
Elliott kicked a penalty goal in the 27th minute to extend the lead to six before the Rabbitohs struck back.
Walker scored his first try three minutes before half time, charging 40 metres down the left hand touch line to score a great individual try. Walker converted his own try to level the scores at 12-all at half time.
It was Walker that gave the Rabbitohs back the lead in the second half, scoring again four minutes after the break. He slipped through the defence from close range, touching down adjacent to the left hand upright. He converted again to give the Rabbitohs an 18-12 lead.
Noble scored again in the 62nd minute with Elliott's conversion levelling the scores at 18-all.
Another Elliott penalty goal in the 71st minute would restore the Roosters' lead, before the Rabbitohs would snatch it back three minutes later.
Centre Tyrone Phillips beat three defenders on the right side to score out wide, and Walker converted to give the Rabbitohs a 24-20 lead with less than five minutes left on the clock.
One-on-one strips by both sides gave both sets of fans heart palpatations, and then the controversy began.
With the clock on zero and the ball having not yet been played, the siren did not sound and the referee let play continue, clearly not realising the game was over.
The Roosters put up a cross field kick on that play, which was bobbled backwards and forwards, with Noble ending up with the ball, touching down and being awarded a try. This levelled the scores at 24-all, before Elliott put a swinging conversion attempt through the posts to steal the win.
The Rabbitohs can feel unlucky at losing this game, but will have 11 days to turn it around before taking on the Cronulla-Sutherland Sharks on Monday-week at ANZ Stadium in round two.
Sydney Roosters 26 (Jack Noble 3, Graeme Su'a Poe tries; Brendan Elliott 5 goals)
South Sydney Rabbitohs 24 (Dylan Walker 2, Brad Croad, Tyrone Phillips tries; Dylan Walker 4 goals)