Interim coach John Morris appears to be in the box seat but it is understood the club's board will consider a range of available coaches including Penrith's Cameron Ciraldo, former Manly coach Trent Barrett and St Helens' Justin Holbrook.

While those four all have links to the club and the Shire, Wayne Bennett's highly regarded assistant at Souths, Jason Demetriou, and the Roosters' Adam O'Brien are also likely to be considered.

The thinking from the Sharks is that putting a coach in place now allows them to start a new chapter in the club's history.

For too long, Flanagan had too much say in the way the Sharks have been run. Ultimately, the only move he had left to play was to resign.

There's no doubt that the uncertainty surrounding his future had taken a terrible toll on his family; a hidden cost that fans and media never see.

But equally critical was that Flanagan had to resign now, while still under contract to the Sharks, so he could receive whatever money was owing to him.

He has until the end of January to contest the breach notice. It's understood he plans to mount a vigorous defence.

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"I intend on responding to the notice issued by the NRL, however I have made this decision in the best interests of the entire club and the players to allow the best possible preparation for the 2019 season without constant speculation and uncertainty as to who their head coach will be," he said in a statement. "This was obviously one of the toughest decisions of my 36-year rugby league career to resign from the head coaching role at Cronulla."

"The last month has taken an enormous mental and emotional toll on my family and myself. I want to single out and thank the incredibly loyal Sharks supporters for their ongoing support and last but certainly not least, I want to thank rugby league fans in general for their overwhelming support and messages over the years and more so over the past month."

Apart from finding a new coach, the Sharks are also bracing for the NRL to hand down its findings into a salary cap investigation.