OUT-OF-SORTS big man Todd Goldstein is on the verge of a "breakout" performance – possibly as early as Friday night against St Kilda – Kangaroos coach Brad Scott says. 

Goldstein, who turns 29 in July, was the 2015 Virgin Australia AFL All Australian ruckman, but has failed to reach those heights this season as Braydon Preuss emerges as a challenger within the club. 

But Scott told reporters Goldstein remained the clear No.1 ruck option at Arden St.

"I think Preuss is going to develop really strongly and we've seen only a glimpse of what he's going to be capable of," Scott said. 

"But Goldy at his best is as good as any ruckman in the competition, in my view, so Goldy's got to get back to that and Preussy's got a long way to go to bridge the gap to Goldy's best. 

"So we'll just keep working with them. We're in a really fortunate position as a club where we've got both of them on our list."

Goldstein didn't take a mark in North Melbourne's past two games before the bye, against Richmond and Carlton, but Scott said that was down to a number of factors. 

"It's a bit more how we're playing," he said.

"We've played three pretty strong key forwards, so we haven't been getting him to push as hard forward … because we want to leave that space open for our other big guys.

"He's a versatile player who's obviously very capable of marking the ball, but he's a great running player as well, so we don't look at one part of his game in isolation – it's just the combination. 

"The combination hasn't added up to his form of the past, but I believe it's a fraction away from turning really strongly." 

The Roos (4-7) have won their past six matches with the Saints (5-6) – starting with a 33-point victory in 2012 – but Scott placed little importance in the record because of the clubs' different stages of development in that time.

"They're a very different proposition this year," he said. 

"I know they've had a challenging last month or so, but the footy they played early in the year was really exciting and they had a lot of exciting, bold ball movement. 

"They were a real handful, so we're expecting that version of St Kilda tomorrow night." 

Nick Riewoldt is set to return against North and Scott said he was considering a three-pronged rotation defence of Robbie Tarrant, Scott Thompson and Lachie Hansen to combat the former skipper. 

Riewoldt, who has been out with knee bone bruising, has been a consistently strong performer against the Kangaroos. 

"We all know Nick's strengths … well, it's probably better to look at his weaknesses – he doesn't have many – because everyone can see the litany of strengths he has got," Scott said.

"I doubt we'll rely on one player to get the job done there – we'll rotate it a fair bit.

"He's really important to them, too, because (Josh) Bruce kicked four last week and I know (Paddy) McCartin they've said probably won't play, but (Tim) Membrey (as well). They've got some versatility there, so it's not just Nick." 

Veteran Lindsay Thomas is available after a lengthy VFL suspension for a crude hit on Melbourne rookie Corey Maynard, but will resume in the state league. 

Scott said Thomas had undergone a "mini pre-season" after not being as fit as required early in 2017 and had the opportunity to be a "really important player" in the second half of the season.