ST KILDA will be without Billy Longer for Friday night's clash with Essendon, with the ruckman to be replaced by Tom Hickey due to a minor hamstring injury.

Longer picked up the injury early in the Saints' big win over Richmond last week, but played out the game.

Coach Alan Richardson said while Longer should be right for next week's trip to Sydney to face the Swans, he was confident Hickey would display the form that made him the club's number ruckman in 2016.

It will be the former Sun’s first senior game since he was superseded by Longer after the opening four matches of the season.

"Billy won't play, but we are really optimistic for next week," Richardson said on Thursday.

"(Hickey) gets his opportunity in pretty good form. We pulled him out of the game on the weekend because we knew Billy was going to be in some doubt.

"We're really excited for 'Hick'. He gets the opportunity, we know last year he played some outstanding footy for the club, and that's what we expect."

Ahead of his first game against his old club, former Bomber Jake Carlisle was a notable absentee from a light training session at a windy Trevor Barker Beach Oval.

However, Richardson said the 25-year-old was a certain starter, and he hadn't been distracted by the looming encounter with a club he walked out on after 85 games.

"He's ready to go, (and) he's going to go out and play another game of key defence," Richardson said.

"It happens be (against) the team he played a lot of footy with and quite a few of his mates, so that's a little bit different.

"He's really focused on what he needs to do for the team. He and (Nathan Brown) have been really good for us down there, and we need the same again."

With third-year key defender Hugh Goddard out for the year with a foot injury and Sean Dempster retiring earlier in the season, the Saints have elevated versatile tall Rowan Marshall off the rookie list to be an emergency for the clash against Essendon.

A late developer, the 201cm Portland product came to attention of club recruiters with two impressive seasons with North Ballarat in the VFL.

The 21-year-old was selected with pick 10 in the 2016 NAB AFL Rookie Draft.

"We've elevated Rowan (because) we've just got a little light on for the big blokes given Hugh Goddard is injured (and) Sean Dempster is retired now," Richardson said.

"Rowan gives us a bit flexibility, so if for whatever reason we lose (a player), then Rowan will give us some structure forward or back.

"He's done a really good job in the VFL, so that was the reason for the elevation."