SYDNEY'S No.1 ruckman Sam Naismith will miss a second straight match with a hamstring injury as the Swans prepare to take on red-hot North Melbourne big man Todd Goldstein.
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Callum Sinclair will again step up in Naismith's absence, as he did in Sydney's narrow defeat to Essendon at the SCG on Sunday.
Swans football boss Charlie Gardiner left the door ajar early in the week for a Naismith return but Longmire confirmed on Thursday that he was "short on preparation".
Naismith will train on Thursday but a decision won't be made until next week on his availability for round four.
Goldstein's performance in the Kangaroos' striking victory over Greater Western Sydney last week was widely acclaimed and he received maximum AFL Coaches' Association votes.
"It's a big challenge for Cal. (Goldstein)'s one of the best ruckmen who's played over the last 10 to 15 years," Longmire told reporters.
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"He's looked like he's not getting any worse off; he's getting better as he gets older. He was fantastic last week.
"His relationship with his midfielders is very good, he has very soft hands, he knows how to find his teammates at ground level – he's an elite ruckman.
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"Over the entire 100 minutes, he rucks every minute of the game, so that's one of the challenges for us, and Cal, in particular, to match him in that area."
Longmire will coach against former assistant Rhyce Shaw for the first time on Saturday at Marvel Stadium and he's been impressed with the impact Shaw's made so quickly.
"He's got them playing really competitive footy – they're the No.1 pressure team in the competition at the moment and they're fierce," Longmire said.
"We saw what they were able to do with the Giants last week. They'll compete, and they'll compete for the entire game, so it's a real credit to the way they're going about it.
"I'm thrilled that Shawry and (Gold Coast's) Stewy Dew are coaching. It's fantastic to have some people out and about doing the same role you're doing.
"I feel good about that but that doesn't mean you go any easier on them on game day. You wish them all the best and hope they go well in their careers, except when they play you … but it's great they've got those opportunities."
Longmire said athletic swingman Sam Reid (calf) was still "a number of weeks" from playing, while there was no update on superstar Lance Franklin (hamstring).