North coach Brad Scott told reporters on Thursday that Wells would miss the Roos' crucial clash with Freo after his foot was accidentally stomped on at training last week. But he confirmed the return of Ziebell after a three- week stint on the sidelines with a right shoulder injury.
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In better news for North supporters, Andrew Swallow (Achilles) will return via the VFL on Sunday. And Scott said the Roos skipper could be available for senior selection as early as next week.
Scott said the Roos were yet to ascertain the severity of Wells' injury.
"He played under a bit of duress last week. It was a good effort to get up to play but he's pulled up sorer this week than he did the week before," he said.
"Someone of Daniel Wells' ability, with his top-end speed and agility, he needs to be right and he's not right, so we won't take him over to Perth.
"It's neither (a bone or ligament issue). We've had every scan you can imagine and they're all clear, but he's still very sore, so we've got to get to the bottom of it.
"But it's definitely not a bone injury, the X-rays, the MRI and CT scans are all clear. As best we can tell at the moment, it's just bruising."
Scott said Swallow had "that sparkle back in the eye" as he prepared for his first game since rupturing his left Achilles tendon against Melbourne in round 18 last year.
The coach said it was hard to set a specific senior return date for Swallow, but said North would not necessarily hold him back until after its round eight bye.
"He's been training really well and with someone like him you would think that if he plays well and gets through unscathed then he pretty much becomes available for selection," Scott said.
"But we'll just watch him and see how he goes.
"But you're right or you're not, I don't think there can be too much grey. You've got to have the courage of your convictions and say he's either right to play or he's not."
Scott also revealed that key defender Joel Tippett would make his club debut against the Dockers, replacing 2013 All Australian full-back Scott Thompson, who was suspended for one week for striking Collingwood forward Travis Cloke last Saturday.
Tippett joined the Roos in last year's NAB AFL Rookie Draft after playing two games with Gold Coast in 2011 and spending 2007-09 on the Brisbane Lions' rookie list.
The 25-year-old, who is the younger brother of Sydney Swan spearhead Kurt, was elevated from North's rookie list ahead of round one after impressing as a key defender in North's three pre-season games.
"We think it's a terrific opportunity for Joel. He's been ready to play senior football all year," Scott said.
Scott confirmed that key forward Majak Daw would return, replacing ruckman Daniel Currie, while Liam Anthony was likely to come into North's team to replace Wells.
Scott said he hoped Daw, who had a posterior cruciate ligament reconstruction last August, would enjoy an extended run in the senior team.
"We're hoping … he can get some continuity in his footy and he can start to show people what he's really capable of," Scott said.
Twitter: @AFL_Nick.
