Tackling addict Dallas Johnson will give North Queensland a shot in the arm as they fight to survive the first week of the NRL finals against Manly on Saturday night.

While more than happy with his players' defensive effort in testing conditions against the Warriors in Auckland at the weekend, Cowboys coach Neil Henry believes having Johnson back for the must-win Sydney Football Stadium clash would be invaluable.

"Dallas is good for 40-50 tackles a game and he's got that big game experience," said Henry as he prepared to assemble a squad of 20 to take to Sydney on Tuesday.

The Cowboys need to upset Manly - who will not be at full strength, with forwards Glenn Stewart and Darcy Lussick still serving time for their part in the Brookvale Oval brawl against Melbourne - to advance beyond week one of the finals.

Sea Eagles winger David Williams is also out for the season with a neck injury.

The fearless Johnson didn't make the trip to Auckland because of recurring headaches following his latest bout of concussion.

The 28-year-old lock, who hadn't missed a game all season before last weekend, did some running on Monday morning but won't do any full contact work until later in the week when the Cowboys set up camp in Sydney's eastern suburbs.

Johnson's renowned defence - he set a State of Origin record with 62 tackles in 77 minutes a few years ago - plays a big part in getting the Cowboys' attack going, which never really happened against the Warriors.

"We'll have Dallas back for the clash with Manly which will be great," said an upbeat Henry.

"We'll be at full strength. We showed a few traits (against the Warriors) that were semi-final traits which we had been missing."

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