Clune and Trent Merrin, products of Albion Park-Oak Flats and Shellharbour respectively, suffered concussions during Saturday's loss to the Sharks and with a five-day turnaround between games, they were always racing the clock to be fit.

The pair failed follow up tests on Monday, preventing them from progressing through the return protocol in time for Thursday's game.

Clune has locked down the halfback role since making his NRL debut in round four, with the Albion Park-Oak Flats product impressing in eight games in the top grade.

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The move saw Hunt shift to hooker, with captain Cameron McInnes moved to lock.

The reshuffle was the trigger for a turnaround in form, with the Dragons a much-improved side with Clune at halfback and Hunt in the No. 9 jumper.

Hunt has made clear his preference to play halfback, however he has impressed at dummy half in recent weeks.

Clune's absence will provide the Queensland representative the chance prove he can be St George Illawarra's long-term No. 7. McInnes will also return to hooker as part of the forced reshuffle.

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While Hunt is expected to earn the nod, St George Illawarra coach Paul McGregor could throw a selection curveball and hand Tristan Sailor his first opportunity in the top flight this season.

The 22-year-old made his debut last year, playing three NRL games.

While the pair will sit out this week, St George Illawarra performance chief Nathan Pickworth is optimistic Clune and Merrin will be cleared to return for round 13.

The NRL confirmed on Monday that match with the Roosters will be played at WIN Stadium on Thursday August 6.

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"They're not too bad," Pickworth said of Clune and Merrin.

"Unfortunately they've failed their follow up test, that's the first stage you've got to get through before you can progress your training throughout the week to progress through the concussion protocol.

"With us being on a five-day turnaround and them not passing today's examination, unfortunately neither of them will be available this week against Souths.

"Hopefully they'll progress through to be available the following week."

In positive news, Mikaele Ravalawa was cleared of a serious knee injury and is expected to be fit for Thursday's match.

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The update came as NRL head of football Graham Annesley defended the performance of his officials in recent rounds at his weekly football briefing.

The senior administrator did not expand on comments made immediately after the Dragons loss on Saturday night, in which he conceded the bunker was incorrect to award Cronulla a crucial try.

Annesley did, however, argue the bunker plays a key role in ensuring as many decisions as possible are correct.

"There will be errors from time to time from the bunker and we tend to focus very heavily on those errors and that's fine, that's part of our game, the scrutiny that our game is under," Annesley said

"But we also need to remember the countless other decisions across the course of the season and across the course of each season, each year, that are correct because of the technology that we use in our game."

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