For more than five decades the Rabbitohs and Panthers have gone head-to-head but only recently have their battles moved into the finals arena.
Both clubs have shared dominant eras in results between each other since 1967 when the Panthers came into the NSWRL competition.
The Rabbitohs barely lost a game to the Panthers in the early stages of their clashes before the western Sydney club began to turn the ledger in the late 1980s.
For 2003 Panthers premiership-winner Scott Sattler, this Sunday's decider is a tricky one - his father John is one of the Rabbitohs' all-time legends but he said his allegiances are with Penrith.
"There wasn't a great rivalry back then when Penrith came into the competition," Sattler said.
"Everyone thought it took a day to get to Penrith from the city back in the 60s and 70s.
Sattler lauds history-making grand final in Queensland
"But I tell you, every time I played against Souths, for some reason we always had problems with them.
"It didn't matter how bad either team were travelling, there were just always problems on the field.
"Souths have always been built on being the blue-collar worker team. They were always willing to give everything no matter the result.
"In the year we won the premiership in 2003 they weren't doing well and we beat them on the siren.
"We played them again later that year out in Penrith but still only beat them by a few points. I never had an easy game against them."
Panthers v Rabbitohs - Grand final
Top 10 - Rabbitohs v Panthers clashes
Round 7, 1968 – Panthers break duck with first victory
The Panthers went winless on three occasions against South Sydney in their inaugural season and found victories tough to come by early on in the head-to-head battles between clubs.
A gritty 13-12 win over the Rabbitohs at Redfern Oval in 1968, their first in club history, was a memorable one for the side, who were coached by Bob Boland,
A try and five goals to Bob Landers got the Panthers in front, although the Bunnies would have the final say at the end of the year, going on to win their 17th title.
Round 8, 1971 – Rabbitohs start dominant run
A 12-10 win over the Panthers in another premiership-winning year may have not looked like much on the way to more glory but it began a dominant period between the two clubs.
Tries to Bob McCarthy and Bob Honan got the Bunnies over the line in Penrith as the opposition struggled to make inroads early on in their club history.
South Sydney had a stranglehold on the Panthers for a further decade with the foundation club winning 16 of the next 20 NSWRL competition games before the tide began to turn in the 1980s.
Round 8, 1985 – Panthers overcome send-off
The Rabbitohs were coming off another finals campaign from the previous season but their cross-town rivals were still looking to break an 18-year finals drought.
Penrith hit some form to string together a three-game winning streak and hosted a Rabbitohs outfit which had slumped to five consecutive losses.
Despite second-rower Brandon Lee being sin-binned, and then sent off, the Panthers held on in the second half to rack up a 16-11 win.
Royce Simmons and Ben Gonzales crossed the line each while Greg Alexander slotted four goals.
Round 14, 1989 – Davidson steals show for Kelly hit
Remembered more for a scrum incident involving Les Davidson and Peter Kelly than the result, the round-14 contest at the Sydney Football Stadium in 1989 had every bit of niggle as the Panthers eyed a new purple patch in the club's history.
The Panthers began a seven-game winning streak against the Rabbitohs with a 19-8 victory at the venue but the aftermath had everyone talking after Davidson clocked Kelly with an uppercut that sent his headgear sailing to the turf.
When asked about the punch after the game, Kelly famously said he was just happy that his head wasn't in it when the headgear went flying.
Controversially, Davidson was given his marching orders by referee Bill Harrigan but Kelly was penalised for the incident, leaving captain Royce Simmons confused by the decision.
Round 6, 2003 – Waterhouse try gets Panthers home
South Sydney's reinstatement to the NRL in 2002 didn't go to plan with results on the paddock but Penrith's previous season was anything but flash either as the two sides met at the Sydney Football Stadium in 2003.
Searching for their first win of the year after five rounds, the Rabbitohs looked on track against a Panthers side who had dropped their opening two games of the season and were nowhere near the premiers they turned into later on.
Tries to Wade McKinnon and Willie Peters started things positively for the Bunnies before Craig Gower produced some enterprising play to send Luke Lewis over on the right edge.
When Tony Puletua levelled the scores in the second half it took some brilliance from McKinnon to ground a ball in-goal.
The Panthers, however, kept the ball alive with six minutes remaining to send Trent Waterhouse over late to win the game 16-14.
Penrith would go on to win 13 of their next 14 games and later claim their second title.
Panthers v Rabbitohs - Round 6, 2017
Round 6, 2017 – Reynolds field goal upstages Panthers
After a thrilling finish in the corresponding match, both sides found themselves in similiar circumstances to start the 2017 season to be sitting outside the top eight after five rounds.
Both sides traded tries early in this encounter before the Rabbitohs took a 20-14 lead until late in the game.
Scores became level when Nathan Cleary produced a clutch sideline conversion for Michael Oldfield's 75th-minute try.
Not to be outdone, it was opposite number, Bunnies halfback Adam Reynolds, who stepped up with the clutch play with seconds left on the clock to land a field goal after Leilani Latu was penalised before the siren.
Match Highlights: Panthers v Rabbitohs - Round 2; 2018
Round 2, 2018 - Panthers storm home to stun Souths
The Panthers and Rabbitohs braced for a scorcher in Penrith as the heat pushed past the 30-degree barrier by kick-off on a Saturday afternoon.
Rabbitohs debutant Adam Doueihi replaced Adam Reynolds in the halves with the now Wests Tiger slotting a penalty goal for the side early.
A spectacular 95-metre try from the Bunnies stole the show in Sydney's west as the visitors skipped to a 14-0 lead through tries to Cody Walker and Damien Cook.
However, when the Rabbitohs lost Greg Inglis and Tevita Tatola to head knocks, the Panthers came home with a wet sail to lay on three unanswered tries in the second half.
Panthers forward Trent Merrin muscled his way over first before Waqa Blake crossed out wide.
From there, Nathan Cleary linked with Tyrone Peachey for the match-winner with five minutes remaining.
Round 14, 2019 - Maloney sinks Bunnies with field goal
Penrith's season was on the improve after sinking to 16th midway through the season but Ivan Cleary's side faced a tough Rabbitohs outfit who were sitting second on the Telstra Premiership ladder.
Three wins on the trot had the Panthers brimming with confidence as Brian To'o emerged on the right edge and Jarome Luai played second fiddle to James Maloney on the interchange bench.
The Panthers did well to get level with Souths through To'o in the 70th minute before Cody Walker's missed field goal attempt from in front was backed up by Maloney slotting a one-pointer at the other end.
Match Highlights: Rabbitohs v Panthers
Preliminary final, 2020 – Panthers add further prelim pain
Penrith were the newcomers on the preliminary final stage while the Rabbitohs were looking to make it third time lucky after their previous two grand final qualifiers led to disappointing exits.
The finals battle between the Panthers and Rabbitohs was the first for both clubs despite their head-to-head clashes spanning five decades.
The Rabbitohs settled the nerves early with a try through Alex Johnston before the Panthers hit back with efforts from Brian To'o and Tyrone May.
Match Highlights: Panthers v Rabbitohs
A try to Dane Gagai in the 49th minute bridged the gap for Wayne Bennett's side until Isaah Yeo split the Rabbitohs up the middle to find Dylan Edwards in support.
It was too little, too late for the Bunnies, who despite crossing again through Corey Allan, were unable get through Penrith's staunch defence.
Qualifying final, 2021 - Pre-game words ignite rivarly
A fiery build-up to the qualifying final between Ivan Cleary and Wayne Bennett ensured a battle for the ages in the opening week of the finals this season.
Bennett's men had gone from being pummelled by the Panthers 56-12 in May this season to narrowly bridge the gap in the second match.
Match Highlights: Panthers v Rabbitohs
However, their 2nd v 3rd battle for a week off took a turn when Ivan Cleary spoke out about tactics being used against his son Nathan.
Bennett returned served, labelling Penrith's block plays to allow Cleary to kick the ball as "illegal".
The Rabbitohs backed up the fiery week with one of their finest defensive displays of the season to march into the preliminary final.
On Sunday, one last chapter will be written this season.