Max King of the Saints marks during round eight, 2021. Picture: AFL Photos

ST KILDA is on the verge of locking in young gun Max King to a contract extension a year before the emerging key forward's current deal ends.

King is signed to the Saints until the end of 2022, which will be his fourth season with the club that drafted him at pick No.4 in the stellar 2018 crop.

But AFL.com.au understands the club has moved to extend him even further than that, with King's new deal expected to be at least two extra years, and potentially beyond.

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Two more years would tie the athletic marking forward to the Saints until the end of 2024.

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King, 20, is one of the leading young tall forwards in the AFL, with his brilliance in the air and at ground level making him already one of St Kilda's most important players.

After missing his first AFL season after recovering from a knee reconstruction in his draft year and then an ankle injury at VFL level, King played 18 games last season and booted 22 goals.

The Saints' No.12 has kicked 12 goals from seven games this season, but has had his inaccurate moments as well, registering 13 behinds.

Despite only playing 25 games at the top level, King, who barracked for St Kilda before it drafted him, is already the Saints' main go-to inside the forward half.

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St Kilda has prioritised King's signature this season despite having next year to run on his deal, having landed contract extensions for important pair Hunter Clark and Nick Coffield earlier this season.

Hunter Clark celebrates a goal during the round seven match between St Kilda and Hawthorn at Marvel Stadium on May 1, 2021. Picture: Getty Images

The in-form Jack Billings remains the highest profile out of contract Saints this season, with the former No.3 pick reaching free agency and generally leaving his contract discussions until later in the season in previous deals.

Midfielder Seb Ross, who is coming to the end of a long-term deal and has returned for Friday night's clash with Geelong, will also hit free agency this year.

Ruckman Patrick Ryder, co-captain Jarryn Geary, midfielder Luke Dunstan, key defender Jake Carlisle and the consistent Jack Sinclair are other Saints without deals beyond this year.