The Saints have listed the star goalscorer as a test ahead of Sunday's home clash against West Coast.
King's comeback from a knee injury last season had been set back by a calf complaint.
It was the latest of many hurdles for the 25-year-old, who managed only 23 games across the 2023-24 seasons before missing last year entirely.
The No.4 draft pick in 2018, King nears his long-awaited return as the 13th-placed Saints (2-4) look to kick their season into gear after a one-point loss to Adelaide.
Star recruit Tom De Koning is also a test after the ruck copped a knock to his back and hip against Adelaide.
Meanwhile, Fremantle ruck Sean Darcy - already managing a concussion - has been sidelined indefinitely after a "relapse" of a calf injury he had been battling during pre-season.
The Dockers are "collecting information" and hopeful to have a timeline soon as the 27-year-old progresses through concussion protocols.
Mason Cox is expected to retain his spot for Saturday's clash against Carlton, after Darcy's absence had opened the door for the former Collingwood ruck to make his club debut in the derby win over West Coast.
Fellow Docker Jaeger O'Meara will undergo surgery for facial fractures he suffered during training and is expected to be ruled out for four weeks.
And the struggling Carlton have their own centre-square woes, with Marc Pittonet joining key forward Harry McKay (concussion) on the sidelines after undergoing hand surgery for a small fracture on Monday.
Four-gamer Liam Reidy is the next cab off the rank, but the Blues are hopeful Pittonet will be a test next round against St Kilda.
Geelong are also assessing the "best path forward for the long term" for Gryan Miers after initial concerns the forward had suffered a full tear of his ACL.
Miers had played the first five games of the Cats' campaign before being withdrawn from the Western Bulldogs' clash last round.
Elsewhere, Gold Coast skipper Noah Anderson will be given ample time to prove his fitness following appendix surgery, with Hawthorn forward Jack Gunston (corked calf) also a test.
Brisbane will be without midfielder Jarrod Berry (calf) for at least three weeks, with Noah Answerth (concussion) also sidelined.
Fellow Lions duo Bruce Reville (leg soreness) and Darcy Fort (illness) have at least proved their fitness ahead of a home clash against Adelaide.
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