Jack Sinclair in action against West Coast in round 19, 2021. Picture: AFL Photos

ST KILDA will be without re-born defender Jack Sinclair for Friday night's clash against Carlton after succumbing to a hamstring injury.

However, the Saints are expected to be bolstered by four reinforcements including ruckman Rowan Marshall and speedster Hunter Clark.

Sinclair injured his hamstring in the dying stages of the loss to West Coast last Saturday and missed main training on Wednesday with scans revealing a low-grade hamstring strain.

Successfully making the move to defence this season, Sinclair was rewarded with a three-year deal earlier this month and is on track for his first top-10 best and fairest finish.

Marshall remains in isolation in Perth and missed Wednesday's session but will fly home in time for Thursday's Captain's Run. 

St Kilda's Rowan Marshall in action during round 18, 2021. Picture: AFL Photos

Clark has been cleared to play against the Blues after suffering a broken jaw in round 13 and trained strongly alongside Jack Higgins (back) and Tom Highmore (hand) at RSEA Park.

"Higgins trained really well today, Clark trained well, Highmore trained really well and Rowan Marshall as well. It looks like we could get four back," coach Brett Ratten said on Wednesday. 

Ratten praised Marshall's professional in allowing him to play off limited preparation and suggested Clark had increased his endurance during his seven-week absence.

"Just his running volume, he's taken to a new level, so he's ticked all the boxes there," Ratten said of Clark. 

"Today was a bit around getting a few knocks around the head area and him feeling comfortable over the ball and he did that really well. Some players react a little bit different from a broken jaw and it can take a little bit of time, but he seemed to be pretty comfortable in that space. 

Higgins is vying for a recall for the first time in three weeks, while Highmore has this week trained with a glove after undergoing hand surgery a little over a week ago. 

Dan McKenzie has been ruled out for a second consecutive match after failing to pass concussion protocols, however Ratten indicated if the match was to be played Sunday he would've been passed fit. 

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Ruckman Paddy Ryder failed to train due to a planned load management schedule but is expected to tackle the Blues. 

A win over Carlton would allow St Kilda to move into the top eight before the rest of the round 20 matches. The Saints then meet Sydney, Geelong and Fremantle to finish the home and away season.