Aliir Aliir appears a touch-and-go prospect for Sydney's season-opening showdown against Port Adelaide, as coach John Longmire considers whether to hold the key defender back for round two.

The emerging 22-year-old star, who missed last year's Grand Final with a knee injury, didn't play in the Swans' pre-season matches because of a toe issue but has had two hit-outs in the NEAFL.

However, while former co-captain Kieren Jack is expected to shake off a sore hip and play at the SCG on Saturday, Longmire was less certain about Aliir's chances of being named in the squad on Thursday evening.

"I'm not sure whether he'll definitely play or not just yet, we'll wait and see how he goes in the training session," said Longmire, who will oversee his 150th game.

"We've been really confident with some of the defenders we've brought in over the pre-season, and he had a bit of a delayed start.

"So we're just looking at whether it's this week or next week in regards to Aliir coming back in the senior team.

"He's very important for us, but we want him to come into the program and play really good senior football, not just senior football."

Jack has been partially involved in training this week and Longmire hoped he'd complete a full session on Thursday without issue.

Whether Sam Naismith or Callum Sinclair partners Kurt Tippett in the ruck will depend on which of the two can best nullify the impact of Patrick Ryder, who's been performing for Port on his return from a year-long doping ban.

"Ryder is a really good player and has been in really good form over the pre-season. We're conscious of that," Longmire said.

"His jump is huge at the moment. He's jumping really high at the centre bounces in particular but also his ruck work around the ground has been of a high standard.

"He's got terrific soft hands, so he gives their midfielders first use of the ball and they've got some really strong midfielders. If he gives them first use of the ball it makes it a real battle.

"Obviously with Darcy Cameron being out injured and not playing, we've looked at Naismith and Sinclair last week. They were both really good in our reserves, so we're confident in either one of those guys playing and partnering Kurt this week."

As expected, Longmire confirmed Isaac Heeney (glandular fever) would not be rushed back for round two, while fellow key players Jarrad McVeigh (calf), Gary Rohan (back) and Tom Papley (knee) are also out injured.