Putting Port Adelaide under frenetic pressure will be critical if North Melbourne is to banish its top eight rivals to a winless start to the season, Roos coach Brad Scott says.

The normally free-wheeling Power have been short-circuited by Fremantle and the Sydney Swans' manic intensity in the opening rounds, with the Dockers dominating contested ball (+26) and the Swans tackling their way to victory (+24).

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Port has been held to just 16 goals combined – after averaging 14.5 per game last season.

However, Scott still rates the Power highly as an offensive threat, and said the Roos must apply the brakes to Ken Hinkley's hard-running side at Etihad Stadium on Saturday night.

"One thing I know is that if we don't pressure well enough Port Adelaide will use the ball really well," Scott said.

"They're probably still the best offensive team in the competition along with Hawthorn."

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After a round one shellacking from Adelaide, the Roos got on the winners' list with an 82-point belting of the Brisbane Lions last round.

Todd Goldstein was a beacon with 23 disposals, 37 hit-outs, seven marks and a goal in a best afield display, and Scott said the ruckman's battle with Port recruit Paddy Ryder could prove pivotal.

"You can be as quick as you like, but if you haven't got the ball it doesn't matter," Scott said.

"The game will be won and lost in the contest as it always is. I think the ruck battle will be crucial and the midfield battle will be crucial.

"Whoever gets right on top there it will probably make it hard for the opposition to defend.

"Goldy's' in good form; we expect him to compete well against any ruck in the competition.

"But Patrick Ryder's a very good player and his best position probably is the ruck.

"They've had some great battles in the past. It will, I suspect, go a fair way to determining the winner on Saturday night."

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The Roos have selected Daniel Wells on a wing, despite the smooth-moving star being under an injury cloud with Achilles tendon soreness.

Wells trained on Thursday and lightly on Friday, but Scott said the "Rolls-Royce" midfielder needed to feel "perfect" to play.

"One thing we know about Daniel is he's a Rolls-Royce and he needs to be feeling at his best to play his best," Scott said.

"We'll only play Wellsy if he's 100 per cent. We picked him because we think he will be OK, but things can happen between now and game time.

"Again, we're really confident, we wouldn't have picked him otherwise. But if he's not perfect he won't play."

North has made two changes to the side that thrashed the Lions, with Nick Dal Santo (hamstring) potentially out for 10-12 weeks and replaced by Ryan Bastinac, and key defender Joel Tippett omitted.

Scott said Tippett – who was dominated by Crows captain Taylor Walker in round one – was not on the outer, but the decision to bring in Robbie Tarrant was due to match-ups.

"We still back Joel Tippett," the coach said. "This week Port Adelaide's forward line is a little bit smaller; we think there's a better match-up for Robbie Tarrant there."