Cronulla’s finals campaign has been rocked by fears of a season-ending Achilles rupture to Shaun Johnson in a 34-18 thumping by a Roosters side.

Johnson collapsed in agony without a hand being laid on him, clutching at his right ankle on the SCG turf.

Given his importance to the Sharks’ season, their hopes of making a post-season dent hit the deck with him.

Johnson’s 22 try assists have been far and away the most by any player in this year’s competition and Cronulla have been a different side when he has been in it.

If early fears of an Achilles rupture for the Kiwi star are confirmed, several months of rehab are in store for Johnson.

An uphill battle for the Sharks too just one week out from the finals, with their seventh straight loss to a top eight opponent hardly comforting.

Hulking prop Royce Hunt added yet more concern when he went down with a dislocated kneecap late, he too requiring the medicab to take him from the field.

Josh Dugan also failed to finish with his own knee issue that he played through for much of the second half.

The Roosters meanwhile did it easy from the outset, ensuring milestone man Mitch Aubusson finished his club record 303rd game in red, white and blue a winner.

Aubusson’s second – from an Angus Crichton grubber that neither he or Ronaldo Mulitalo could get a handle on at first grab before the veteran reeled it in – had the Sharks on the ropes.

An eye-catching return of serve from Mulitalo, with legs and arms in every direction as he flew for the corner, came after a long bust by Katoa.

The half-time break and Johnson’s horror prognosis took the sting out of proceedings somewhat.

A sublime short-side raid from the Roosters kept the points coming, Keary again on the score-sheet from a 50-metre play he featured in twice.

Late tries for Braden Hamlin-Uele and Manu followed before the Roosters make-shift fullback ended his night early with a sin-binning for a professional foul.