A LINGERING back complaint continues to hamper Western Bulldog Tom Boyd's pre-season, placing his start to the season in doubt.

Boyd has failed to train alongside teammates in the main group over the past two days as he works through symptoms from the injury that ended his 2018 campaign after round 18.

The 23-year-old, who is preparing to enter his fifth year of a multi-million dollar, seven-year deal at Whitten Oval, has been confined to his own individual running program.

Combined with light duties during last week's training camp in Mooloolaba, Boyd's lack of high-intensity conditioning has put his hopes for round one action in jeopardy.

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Premiership teammate Liam Picken remains on restricted contested duties, despite completing a large bulk of ball work with teammates on Tuesday.

Picken hopes to play again for the first time since suffering a nasty concussion in last year's JLT Community Series that ruled him out for the entire season.

Exciting draftee Bailey Smith has increased his training output after a modified start to the summer coming off an Achilles concern.

Smith will be hoping to form a midfield partnership with Tom Liberatore, who is on track for round one after a month of full training.

Lukas Webb, who last month trained for the first time without his neck brace since July, also trained strongly on Tuesday.