North Queensland officials have notified the NRL judiciary they will challenge charges against superstar halfback Johnathan Thurston and young forward Tariq Sims on Wednesday night.

The club lodged the necessary paper work before Tuesday's midday deadline.

Thurston will plead not guilty to a grade two contrary conduct charge, threatening to rule him out of next month's deciding State of Origin game after his collision with referee Matt Cecchin at the weekend.

If that fails, he'll then attempt to have the charge downgraded in the hope of being cleared to play in skipper Darren Lockyer's last Origin game.

Sims, touted as a NSW Origin bolter, will try to have his charge downgraded from a grade two to a grade one, allowing him to play on Sunday afternoon against Penrith at Centrebet Stadium.

Thurston, Sims and Cowboys' football manager Peter Parr were forced to fly to Sydney a day earlier than planned because of the uncertainly surrounding flights affected by volcanic ash.

They will meet solicitor Geoff Bellew, who is rushing back from Los Angeles to discuss their defence case with Thurston before Wednesday night's crucial judiciary hearing.

Meanwhile, Melbourne prop Sika Manu has taken the early guilty plea on a grade one dangerous contact charge for unnecessary use of the knees on Wests Tigers' backrower Gareth Ellis' calf and will be free to play this weekend.

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