CALLUM Mills is still battling an Achilles injury and is no certainty to start the season, Sydney coach John Longmire has revealed.

The newly appointed co-captain was sidelined for the Swans' elimination final loss to Greater Western Sydney last August with the same problem and is yet to fully recover.

Longmire said it was an ongoing problem Sydney would take no chances with.

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"He's worked so much to get that Achilles right," Longmire told AFL.com.au.

"Often with these injuries you take two steps forward and one step back. That's happened a little bit over the pre-season with him."

Mills has completed parts of training but has not finished an entire session with the main squad.

Longmire said the 24-year-old was "tracking forward" but could not put a timeline on his progression.

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"Where that leaves him for round one, we're not sure just yet," Longmire said.

"We'll play him when he's right and he's right for the entire season.

"He's been doing some drills but we're really mindful we're not going to push him too hard if it sets him back two to three weeks."

Mills played just one match – round 23 against Gold Coast – in the final month of the Swans' season.

The Swans coach said he had no regrets playing Mills then, adding that Achilles' injuries needed to be used to heal.

"We hope to introduce him to full training sessions over the next week or two and then to develop him into competitive training work," he said.

"That's the plan but we'll be guided by how his Achilles is responding.

"We know he's giving himself every chance to be available as soon as he can."

Longmire said Ollie Florent (ankle) and James Rowbottom (hand) would be "a week or two, max" from returning to training.