ST KILDA defender James Gwilt has been replaced by Tom Simpkin in the Saints' 25-man squad for Sunday's clash against Gold Coast after suffering a hamstring injury at training on Friday.

Gwilt, who has played every game this season, was put on notice earlier on Friday by coach Alan Richardson, who said he had fallen short of expectations the past fortnight in losses to Hawthorn and Carlton.

The 27-year-old had been named on an extended interchange bench ahead of Sunday's clash, as the Saints considered options to shut down Gold Coast's three-pronged tall forward line.

Simpkin played his only game this season against the Hawks in round seven.

"It may be that we make a change there, but certainly if he (Gwilt) plays he'll have to play on a tall," Richardson said on Friday morning.

"We expect a fair bit from Jimmy. He's an experienced player in a relatively inexperienced team."

As well as Simpkin, Richardson said third-year rookie Cameron Shenton, who played his first game of the season against Carlton on Monday night, was capable of playing taller than his 188cm suggested.

Experienced defender Sean Dempster was another third-tall option.

He said the back six would need to be on-guard against young Suns Tom Lynch, Sam Day and Charlie Dixon, who were superb against North Melbourne in round seven.

"They're certainly marking the ball very well … we'll have to be really strong defensively," Richardson said.

"We're really pleased with the way (Josh) Bruce and (Luke) Delaney in particular have gone.

"Both guys didn't concede a goal on [Monday night] to (Lachie) Henderson and (Levi) Casboult.

"We're in reasonable form in terms of defending talls, but it'll go to another level this week … I think our guys are up to it."

At the other end of the ground, an over-reliance on star goalkicker Nick Riewoldt was an issue against Carlton, but Richardson said he would back the same group of forwards to make amends.

The coach called on Rhys Stanley to regain his early-season form after a quiet match against the Blues that saw him finish goalless with six disposals and one mark.

"We think his footy has improved, [but] like our group he's dropped off the last couple of weeks," Richardson said.

"As we've lost some experience out of the team there's been a bit more responsibility come to people like Rhys that are in that middle tier, in terms of experience.

"He'll learn to cope with that.

"We need him to respond in a really positive way. Not only does it take a bit of pressure off other forwards, he's been pretty significant in our better performances."

Club champion Jack Steven, who has played the past five matches, has been on a modified program this week as part of his return from a serious foot injury, but Richardson said he was "right to go" against the Suns.

The coach said midfielder David Armitage was doing straight line running as he returns from a serious knee laceration and was a chance to return after the Saints' round 10 bye, either in the VFL or at senior level.

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