“Heath was out on the training track today but he still felt lethargic and flat. We just got the results back and they’ve now confirmed that he has glandular fever,’’ senior coach John Longmire said.

“It’s very disappointing for Heath and for the team as he’s been in good form all year and plays a key role in our defence. However his health is our main concern and we’ll make sure he now gets all the rest he needs.’’

Swans doctor Nathan Gibbs said Grundy had not been ruled out of playing in the finals series if the team progresses beyond this Saturday.

“We haven’t ruled him out as recovery from glandular fever can be unpredictable,’’ Gibbs said.

“We don’t know when he’ll be back but at this stage we’ll just monitor him week by week as necessary.’’

The Swans have made two changes to the side that beat Brisbane last weekend, with Roberts-Thomson and Sam Reid coming in, for Nick Malceski and Lewis Jetta.

Reid missed the Brisbane game with calf tightness but trained sharply today and is fit to play in what will be his first-ever AFL finals game.

Six Swans players will be making their finals debut - Reid, Gary Rohan, Alex Johnson, Luke Parker, Craig Bird and Matt Spangher.

Longmire said they all deserved their spot. “Those boys will get to play their first final this week which is great for the future of the footy club, but also great for the here and now. They’ve earnt their game, every one of them, and hopefully they give a good account of themselves,’’ Longmire said.

The coach said he was confident Roberts-Thomson could fill the role left by Grundy’s absence.

“Lewie Roberts-Thomson has played in defence for us for a long time. He is used to playing in that part of the ground so we’re confident he’ll be ok,’’ Longmire said.

“Heath has been an important player for us but it’s great we can bring Lewie back in, who is a premiership centre half back for us. He is a good player and knows his role, and he will be part of an experienced defensive six with Ted Richards and Rhyce Shaw there as well.

“Everyone is up and about, they’re all looking forward to the first final. We know how tough it is going to be against St Kilda but we’re looking forward to getting down there and playing.’’

The team to play St Kilda is:

B: R.Shaw, T.Richards, T.Kennelly
HB: M.Mattner, A.Johnson, N.Smith
C: JP.Kennedy, A.Goodes, J.McVeigh
HF: R.O'Keefe, S.Reid, G.Rohan
F: L.Roberts-Thomson, M.Spangher, B.McGlynn
Foll: S.Mumford, J.Bolton, K.Jack
I/C: C.Bird, D.Hannebery,L.Parker, J.White    
Emg: L.Jetta, N.Malceski, M.Pyke

In: L.Roberts-Thomson , S.Reid
Out: N.Malceski, L.Jetta