Burgess confirmed on Wednesday he'd succumbed to a left shoulder injury, ending a glittering career as one of the game's most fearsome forwards.

"This decision was one of the hardest decisions I've had to make in my life, however the decision was out of my hands essentially," Burgess said.

"I am no longer able to be myself day-in, day-out on the training field and consequently the playing field.

"I have loved absolutely every minute: the highs, the lows, the grand final, coming home, my injuries, my dates with the judiciary.

"It really has been a fantastic ride."

Burgess battled shoulder issues early in his career, but endured the most damage this season when he needed a clean out in June and later suffered an infection.

The Rabbitohs said it was only then a chronic problem was discovered.

Burgess still has three years to run on his multi-million dollar deal, and the Rabbitohs have already had casual discussions with the NRL on how it will be managed.

Under NRL rules, the salary cap auditor will consider if Burgess was unable to ever return and whether a single event that caused the injury could be determined before ruling whether his salary will count in the cap.

The NRL must also consider if a degenerative issue could have been predicted based on a similar issue prior to when he signed his last contract last September, unless an unrelated event has resulted in a rapid deterioration.

"There'll obviously be questions about what Sam's retirement means for South Sydney's 2020 salary cap and beyond," NRL CEO Todd Greenberg said.

"There are rules surrounding these matters and it's important we take our time to work through the facts with South Sydney in a considered and methodical manner."

Regardless, Burgess will go down as one of the NRL's great forwards after arriving from Bradford in 2010.

He played 182 games for Souths and was Clive Churchill Medallist despite suffering a debilitating facial fracture in their drought-breaking 2014 grand final win.

Apart from a brief switch to the 15-man code which culminated in representing England at the 2015 Rugby World Cup, Burgess was named Souths' player of the year in 2014, 2016 and 2017.

"Sam Burgess has been a true champion of our game," Greenberg said.

"He inspired so many players from the UK to want to play in the NRL. Our competition is stronger today because of Sam's influence."

The announcement will leave a leadership void at Redfern.

Greg Inglis retired suddenly earlier this year, while fellow former captain John Sutton has also finished up.

Damien Cook, Cameron Murray and Adam Reynolds are expected to be the leading contenders to assume the captaincy.

David Fifita, Jai Arrow and Tyson Frizell have been mooted as back row replacements, all of them off contract at the end of 2020 and available to be approached from Friday.

"He was one of the drawcards for me in coming to coach at South Sydney," Souths and England mentor Wayne Bennett said.

"I was lucky enough to coach Sam in the All Stars game in 2010. I'd had heard so much about this Englishman that I had to see him for myself.

"I'm glad to have played a small role in his career and I feel blessed that he has been part of mine. I know he has made the right decision."

SAM BURGESS' CAREER:

* NRL Games: 182

* Tests: 25 (23 for England, 2 for Great Britain)

* Tries: 44

* Premierships: 1 (2014)

* 2014 Clive Churchill Medallist

* 2014 RLIF international player of the year

Australian Associated Press