ST KILDA will be forced to make at least one change for Friday night’s clash against Collingwood, with Blake Acres’ high ankle sprain expected to see the teenager sidelined for further five weeks.

Seb Ross appears the most likely player to come in for Acres, however Sam Dunell’s form in recent weeks for Sandringham will create a welcome selection headache for Alan Richardson at Thursday’s match committee meeting.

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Meanwhile, the first-year coach admitted that David Armitage was “probably less likely than likely” to return from a deep knee laceration against the Magpies, the possibility of him lining up in the midfield adds significant grunt to the Saints engine room.

"He (Armitage) is a chance,” Richardson said on Thursday morning.

We'll see how Dave goes [at training]… He wants to get out there and help but we've got to make sure we do the right thing by him and the team."

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The left footer hasn’t played since St Kilda’s round four loss to Adelaide and his value cannot be underestimated following his fifth place finish in the last year’s best and fairest.

“His training program with respect to high grade agility, tackling and physicality has only really ramped up this week.”

Fellow lefty Seb Ross has spent the vast majority of the season plying his trade in the VFL, although he did gather 18 disposals in the Saints’ Anzac Day match against Brisbane in Wellington.

He’s been far more prolific for the Zebras, averaging 27 disposals, 6 clearances and over a goal per game in his five outings for Sandringham.

According to his coach, Ross is well-placed to return to the senior fold against the Magpies.

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“Sebby couldn’t have done any more,” Richardson said.

“He’s been in really good form and he’s a significant chance to play on Friday night.”

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While Dunell doesn’t offer the midfield drive of Ross or Armitage, it’s his strong marking and exceptional work-rate that has him in the frame for his first senior game since round 19 last year.

“Sammy has been very consistent,” Sandringham coach Simon McPhee said in his mid-season VFL player review late last week.

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“Again, he shows excellent leadership and can impact games of footy. He’s been pushing for senior selection for a few weeks now.”

Of the other players who may be in contention for a call-up either this week or in the near future, Tom Lee looks to the most likely to play once his form demands attention.

“Tommy, on the back of a fairly slow start to the season with two shoulder reconstructions, is building,” Richardson said.

“His form has not been outstanding… He’s been a bit scratchy up until now but he’s a guy we want to get in when he’s ready.”

Similarly, elusive wingman Daniel Markworth will be monitored closely by the Saints coaching staff.

“His form has been OK. The guys that are playing in the positions we’ve identified for Daniel, like Jack Newnes, have been in pretty good form.”

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“He’s just going to have to continue to improve and grow. He’s a fantastic young man. His dedication to his footy is really impressive.”