DOUBT continues to swirl around Harley Bennell's availability for a Fremantle comeback against Carlton after the injury-plagued midfielder trained away from the main group on Wednesday morning.

Bennell had been primed to play in last Sunday's spiteful Western Derby before suffering a "half-centimetre fascial strain" in his troublesome left calf during a dominant performance for Peel 11 days ago.

Dockers coach Ross Lyon was confident Bennell would miss only one match and expected the 25-year-old would return before the end of his third season in the west.

MATCH PREVIEW Dockers v Blues

But the former Gold Coast jet wasn't given a timeframe on Freo's official injury list on Tuesday, and failed to join in main training during the 45 minutes open to media at the club's Cockburn headquarters.

Bennell and warhorse ruckman Aaron Sandilands – also battling a calf strain – completed extra running without hitting top pace.

Complicating Bennell's return is WAFL-alignment club Peel having the bye this weekend.

He has made just two appearances for Fremantle in nearly three full seasons, but has been guaranteed another contract.

Sandilands' future remains unclear, amid questions whether the 35-year-old will be fit to play again this year.

Lee Spurr has announced his retirement and, with Michael Johnson and Danyle Pearce already confirmed departures, the rebuilding Dockers' list will be significantly younger next year.

Superstar midfielder Nat Fyfe, who wants to face the bottom-placed Blues on Sunday, joined in skills work on Wednesday after five weeks sidelined by a hamstring strain.

VETERANS' LIST Catch them while you can

He is listed as one to two weeks away by Freo's medical staff.

Stephen Hill walked laps after yet another quad complaint – his fifth soft-tissue setback this year – which could have ended his season.

The Dockers will have to make at least two changes this week to replace Hill and Andrew Brayshaw (jaw).

Key defender Joel Hamling (calf) was also in rehab and is likely to miss the next fortnight.

The 13th-placed Dockers face a daunting trip to Geelong before hosting Collingwood in the final round, in what could become a farewell game for several veterans.