MYSTERY surrounds the early season availability of Essendon captain Dyson Heppell as he continues to recover from off-season foot surgery.

Heppell was unsighted on the training track for a second consecutive week on Thursday, just 16 days out from the season opener against Fremantle. 

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The 27-year-old had a screw removed from his foot last month after previously developing pain following the operation in September. 

Now doubt has been cast over his chances of returning in the early parts of 2020, having barely trained with the main group all summer. 

Heppell will miss Monday's Marsh Community Series date with Geelong in Colac on Monday, along with key defender Cale Hooker.

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Assistant coach James Kelly was unable to put a timeframe on the skipper's availability following his latest procedure. 

"Guys like Hepp and Hooksy are still a little way off," Kelly said. 

"We're confident that if we don't have some players in, that the other players we bring in can play the role we need them to (early in the season)

"In terms of names, there won't be a couple of guys early in the year, but we're not worried about that.

"He's (Heppell) progressing really well, he's getting the work in that he needs to." 

Hooker received a round of applause from teammates as he completed the first 30 minutes of Thursday's two-hour session with the main group. 

However, he then spent the rest of the session with the rehab group as he overcomes a hip injury that required surgery and will rule him out of at least the opening fortnight of the season. 

Incumbent No.1 ruckman Tom Bellchambers also re-joined full training following knee surgery in early February and could play some minutes against the Cats.

Irishman Conor McKenna had his first big session since returning from his homeland last week and trained as a forward in a match simulation session overseen by coach-in-waiting Ben Rutten.

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Kelly said McKenna remained in the frame to face the Dockers on March 21 and was a chance to play in Colac.

Recruit Jacob Townsend completed individual running away from the main group, before heading from the track following a long chat with medical staff. He was later spotted with an ice pack on his right knee as he manages a knock from the Bombers' first Marsh Community Series match against West Coast. 

A handful of Bombers trained indoors including Devon Smith, Martin Gleeson, Andrew Phillips and Will Snelling.