Lachie Henderson will return for his first game of the season, but it won't be alongside fellow defender Harry Taylor as doubt grows on his latest foot setback.

Taylor has been ruled out for a second consecutive week against Melbourne on Saturday night with a fresh tendon injury on his troublesome left foot.

The veteran has only played five games this season.

After going down in round one against the Demons with a plantar fascia, Taylor missed two blocks of matches before soreness developed in round 16 against Sydney.

"Harry's not available this week, we're still not exactly sure on when he'll be available," coach Chris Scott said on Thursday.

"We're optimistic he'll be available the following week, we're just not absolutely sure. It's in the same foot, in the same area, more related to a tendon."

It's better news for Henderson who will return for the first time this year after three knee surgeries dating back to October.

While playing his five matches in the VFL as a defender, Scott remained tight-lipped on where Henderson would line up against the Demons with a forward role a strong possibility.

"He's absolutely in full fitness now and in good form. I'm not prepared to go as far as saying where he's going to play. He's worked really hard, he's really diligent," Scott said.

Scott confirmed the news that luckless 21-year-old Nakia Cockatoo will require surgery on the PCL he re-injured in his VFL comeback on Sunday.

While stopping short of ruling Cockatoo out for the season, the injury-plagued livewire looks all but certain to be sidelined until 2019.

Ruckman Zac Smith has bolted into consideration after two weeks in the VFL following a back injury.

While incumbent big man Rhys Stanley was on light duties on Wednesday, a Smith return would pit the former Sun against Max Gawn who outclassed him in the season opener.

With Wylie Buzza underperforming in last week's loss to the Crows, Scott has given plenty of thought to the make-up of his forward set-up and whether to go in with a second ruck.

"The second ruck in a strange way is less important against Gawn because he rucks so much," Scott said.

"In our view it's more a battle between the two No.1 ruckmen.

"It's been a little bit of a challenge for us to get some continuity there (second key forward). Henderson back and available adds another one into the mix as well."

Untried draftee Charlie Constable and mature-age recruit Stewart Crameri will need to continue strong VFL form to earn a senior berth, Scott saying they had both been overlooked.

Lincoln McCarthy trained on Wednesday, however looks set to miss his fifth week in a row with a hamstring injury. A return in a fortnight looks likely, the Cats' VFL side having the bye next weekend.

Meanwhile, AFL umpire Troy Pannell was on hand for match simulation on Wednesday, part of the Cats' education process.

"We try to get an umpire down as often as possible," Scott said.

"We're in the fortunate position that Troy's been available to come down given he umpired our game last week, he's got some insights that would be fresh in his mind.

"Similar in the way that our game style evolves through the year, I think the umpiring interpretations evolve as well.

"Sometimes they're not necessarily directed by the umpiring coaches or the powers that be at the AFL, it's just the way that it happens."