The Eels booked their passage to the quarter finals and knocked the Rabbitohs out with a 24-11 win built on a quality game from halves Corey Norman and Mitch Cornish.
From the first set Semi Radradra reeled in a short kick-off and was on the end of an overlap a couple of plays later to start the scoring. Bryson Goodwin showed far more urgency than Vai Toutai in chasing down a John Sutton kick early in the count to get his side on the board. A wonderful running set got the Eels in range for Corey Norman to fool everyone with a show and go and a 10-4 lead.
A beautiful right-side shift from the Eels was polished off with a chip from Toutai to impressive youngster Bevan French for a 14-4 half-time lead.
Cam McInnes darted over for a bonus try following his side's regather of the kick off to start the second half before Toutai stretched the lead when he cashed in on an overlap created by a series of late offloads. Souths needed a score to get back within a try but were frustrated by the Eels' defence and a late Radradra try helped the Eels top their pool on for-and-against.
Speaking after the loss, Rabbitohs recruit Damien Cook was frank about his side's failed title defence.
"It was a little bit disappointing to end our title defence that way, but credit to Parramatta for doing what you have got to do at the Nines," Cook said.
"They kept the ball off us and defended better than us as well. At the end of the day you can't win the game without the ball and that's why we are knocked out of the tournament."
Manu Ma'u believes his Eels team are finding form at the perfect time after beating South Sydney to secure a spot in the quarter-finals.
"It is pleasing mate, we were struggling yesterday but it's nice that we have found a bit of form," Ma'u told NRL.com.
"Ahead of the quarter-finals we need to stick to our game plan in the middle. In the first game we just threw the ball around and didn't have anything going forward. If we win the middle the edges come in and we score plenty of tries out wide."
Parramatta Eels 24 (Radradra 2, Norman, French, Toutai tries) def. South Sydney Rabbitohs 11 (Goodwin, McInnes tries)