THE RETURN of St Kilda utility Sam Gilbert will help offset the loss of veteran Nick Riewoldt for the must-win clash with fellow finals aspirant Melbourne at the MCG on Sunday, Saints coach Alan Richardson says.

With three rounds remaining, 11th-placed St Kilda is one of four teams on 10 wins, but sits a whopping 10 per cent outside the top eight.

Riewoldt's absence – after suffering concussion in last week's stirring win over West Coast – could hurt the Saints given his experience and versatility, but Richardson said Gilbert would be a welcome addition after overcoming a hand injury.

The Saints coach said the club was developing a group of players who could play in multiple positions, also citing the likes of youngsters Blake Acres, Jack Sinclair, Jack Billings and Jack Steele, and was pleased to add experienced left-footer Gilbert to that mix.

"'Gilbo' can play back and play really good footy there, he can be a big body and really hunt up through the midfield, he can also give us a bit of presence in front of the ball for whatever reason, in the absence of Nick if we need a bit of size. So we're pleased to have him back," Richardson said before training at Trevor Barker Oval on Saturday morning.

Richardson revealed Riewoldt – who last week announced he'd retire at season's end – wasn't happy to be ruled out.

"He was pretty close but, like any footy club, if they're not at 100 (per cent) they don't get anywhere near getting to the line. He wasn't quite right," Richardson said.

"He certainly challenges the doctors – that's an understatement. They've asked for mouthguards and headgear after the way he reacted to their call to not bring him back on (last week).

"That's been his greatest strength throughout his whole career – he's a driven, ambitious, competitive person who wants to play footy and wants to do the right thing by the footy club and his team. So he got frustrated but the right call's been made."

The clash with the 10th-placed Demons is a virtual eight-point game and Richardson said his players were looking forward to playing a big game in front of what promises to be a good crowd.

When the two developing teams met in round one, St Kilda led by four goals early in the second term before going down by five goals, but Richardson insists that result has little relevance now.

"They're a different team, we're a different team. We spent a little bit of time looking at that (game) but not a lot of time. We've moved on and we've improved with our footy, (and) we think they have too, so it doesn't carry a lot of weight," he said.

A loss wouldn't necessarily be fatal to the Saints' finals hopes but it would make it particularly difficult given they face premiership threat Richmond in the final round.

"Tomorrow still keeps it in our control," Richardson said.

"(If) you win 13 games you're very unlikely to miss, whereas if you lose tomorrow then it's very much up to what other teams do. (A loss) doesn't mean that you miss but it means, particularly when our percentage is low, we (would) need a bit of luck.

"It's a good position to be in, that with three weeks to go … (we) have our own destiny in our control."

If they do make the finals, hamstrung veteran Leigh Montagna is expected to be available, but Richardson said he wouldn't be guaranteed a game given he would have missed five games by then. 

The coach said a decision was nearing on the 33-year-old's playing future.