Veteran defender Heath Grundy says fellow Swans defender Aliir Aliir is capable of being a special player.

Aliir played 13 games last year in his maiden campaign before a knee injury cost him a place in the grand final.

The athletic 22-year-old key-position back impressed with his agility and running, playing 11 straight matches and effectively replacing longstanding defender Ted Richards, who retired at the end of last season.

Aliir hasn't played in the pre-season because of a toe injury, but is likely to get a run this week in the seniors or reserves.

"He made huge inroads last year - he was fantastic for us," Grundy said.

'He's been back training for a few weeks now and he's shown his ability in certain drills that he's capable of being a pretty special player.

"We expect him to keep improving."

With Richards gone, the 30-year-old Grundy is the longest-serving specialist defender on the Swans' list, having logged 213 games.

The 2012 premiership has put together arguably the best back-to-back seasons of his career, finishing third in the club's 2016 best and fairest after placing fourth the previous year.

He's relishing mentoring the emerging crop of Swans backs.

"I'm really enjoying that learning phase and teaching guys and helping them develop as players as well," Grundy said.

Aliir is one of several youngsters injected into the Swans' defence in recent times, with Harrison Marsh, Callum Mills and Jake Lloyd spending time down back.

Grundy was philosophical about defensive spots being occupied by players like Lloyd and Mills, who came to the club as midfielders.

"The game is heading that way. You've got to be able to play a number of different positions," he said.

"It's exciting we've got multiple options down there for us, which gives us different looks all the time, which is something that we need this year."

He has mixed feelings about the suggestion from coach John Longmire that Mills could play minutes this season in the midfield.

"I don't mind him at half-back - he gets across and helps pretty well," Grundy said.

"But I'd also like to see him in the midfield; he'd be pretty handy in there for us as well."