They've been the dominant side in the Holden Cup this season and the Penrith Panthers started their finals campaign strongly, thumping the Sharks 28-6 at Allianz Stadium.

Sharks captain Jayden Bailey opened the scoring for Cronulla, diving over from dummy-half after seven minutes.

Panthers fullback Dylan Edwards came close to pegging one bag for his team five minutes later only to lose possession in the Sharks' in-goal.

But Penrith levelled the scores midway through the first half when Dean Blore broke clear to score.

The Sharks had a try denied after half an hour when Joshua Tuilagi appeared to have crossed in the corner, with a successful Captain's Challenge from the Panthers resulting in the on-field try decision being overturned.

The teams went into the break level at 6-all but Penrith quickly took control in the second term, with Reed Izzard scoring after a Sharks error from a kick.

There was a sense of deja vu with the Panthers' next try with another kick spilled by the Sharks, with Izzard this time laying on a try for Daniel Brown.

When Wayde Egan darted out of dummy-half and fooled the defence with a dummy the Panthers led 20-6, and when winger Ratu Tuisese scored the Panthers had secured their place in the preliminary finals in a fortnight's time.

A spectacular 90-metre team Panthers try in the final moments completed the rout, with Braidon Burns collecting a Dylan Edwards kick to score.

The Sharks will be battling to keep their season alive against the Roosters next Saturday.