ST KILDA midfielder Jack Steven will miss Sunday's crunch clash with Collingwood at Etihad Stadium as he recovers from a punctured lung.

Steven, 27, was injured in the last quarter of the round two match against West Coast. 

He will be fit to face Geelong in round five. 

"Unfortunately Jack Steven won't play. He's been ruled out for another week," St Kilda coach Alan Richardson said at Linen House Centre on Thursday.

The three-time Trevor Barker Award winner has been training and took to the field on Thursday, but a doctor from outside the club ruled Steven out. 

"(He was) close, but in the end it was an external expert that said he needs another week," Richardson said.

"It's quite frustrating for Jack. He trained strongly last week, let alone this week. He wants to be out there playing but clearly this is about his health and wellbeing, and Jack's one of those guys that you do have to protect from himself a bit. 

"You love those sorts of players but he'll miss another one." 

The Saints are relatively confident fellow onballer David Armitage will return from a groin injury.

"He needs to get through today's session, and given we don't play until Sunday, it's a pretty meaningful session," Richardson said. 

"We're optimistic and if he gets through, then we'll bring Dave in." 

Armitage finished equal-10th in the best and fairest last year (with retired defender Sean Dempster) despite carrying a back injury throughout the season that limited his running. 

Richardson admitted high draft picks Jack Billings and Paddy McCartin were down on form against the Brisbane Lions last Sunday. 

Both had limited game time in that match – McCartin played 58 per cent while Billings spent 65 per cent of the contest on the field.

Nick Riewoldt spent more time forward and booted three goals in a typically impressive display. 

Billings was drafted third overall in 2013 while McCartin was the first pick in 2014. 

According to Champion Data, Billings' form since 2016 has him ranked 33rd out of 52 players drafted in the same year who have lined up in at least five games. 

McCartin is ranked 46th out of 52 on a similar measure. 

"Sometimes it's a balance thing, particularly for Paddy up front," Richardson said. 

"Rooey (Riewoldt) was going pretty well, so that means less time for Paddy. The reality is if you perform strongly, you force that situation. We think Paddy probably didn't have his best game.

"JB (Billings) is not dissimilar. JB's had a really strong pre-season. His form leading into the season's been really positive. He didn't have his best game (and) we'd expect him to bounce back this week."