WHETHER it was fate or just plain good luck, Tom Collier's return to the Lions line up last week has given him the inside running to fill the boots of injured vice-captain Jed Adcock.

While the quietly spoken 20-year-old has played down his chances of stepping into Adcock's role, coach Michael Voss was sufficiently impressed with Collier's game to indicate he's more than a fair chance of running out against Fremantle on Saturday.

"Someone else is now going to have to stand up and fill that role, and I'm confident because our guys have been able to do that so far this season," Voss said on Monday.

"Guys like Tom Collier, who just came back into the side, and Pearce Hanley might have to share some of the responsibility of that role."

Collier has played four matches so far this season, including round one against West Coast and matches against Geelong, St Kilda and the Cats again at the weekend.

And while Adcock's season ending ACL injury was a hammer blow to the Lions, Collier said he and his teammates were ready to fill the void.

"I think we've got good depth in the group and lot of guys can step up," he said.

"Obviously it'd be nice to fill his spot, but I've got to keep doing what I do best and keep improving on what I did on Saturday night, and whether that's stepping into his spot I don't know.

"Jed is one of our leaders. He plays in the backline and midfield and is great at organising things around the stoppages and in general play. And that's what we'll lose; he provides run and carry but it's that organisation and leadership we'll miss."

Collier put on 8kg of muscle in the off-season and showed the benefits of it in one of his strongest performances on Saturday night.

He had 17 possessions and attacked the ball with ferocity against Geelong.

Collier said being in and out of the team so far this season had given him a chance to work on some aspects of his performance.

"I just had to go away and fix up a few little things in my game and get some continuity back," he said.

"I had a good pre-season then had a little setback, played the first game against West Coast and I wasn't up to scratch so I had to fix a few things and get that confidence back.

"I went back (to the reserves) knowing what I had to work on. I wanted to go back and really back myself in the air and get the footy more; take some marks and get my confidence.

"Any time I get a game (in seniors) it's great. Hopefully I can string a few together.

"The more games you string together the better you feel and more confident you get; that's only natural for any player."

Collier said it took him a little while to get back up to speed with the AFL on Saturday night, but by the end of the match he was fine.

He said the continuity in the backline, with defensive rocks Daniel Merrett and Joel Patfull joined by runners Josh Drummond, Ash McGrath and Joel Macdonald, was something that continually developed for the Lions.

"We've had that confidence improve with our ball movement and each week we're getting better at it."