THE BRISBANE Lions are monitoring the progress of uncontracted Collingwood defender Jack Frost as it seeks to add key defenders to the list. 

Frost is among several options the Lions are understood to be interested in during the upcoming trade period after identifying a need for more experience in defence.

The Magpie did not play a senior game after round 12 but has racked up 54 at the highest level since arriving at the club as a rookie in 2013.

The 24-year-old suffered an ankle injury in the VFL final against Williamstown on Saturday, but X-rays cleared him of any break and he remains in line to play for the Magpies in the VFL preliminary final in a fortnight.

Frost has been a good performer in the VFL and looked a class above that level at times, having struggled early after an interrupted pre-season due to a hip problem.

Whether a move north would be attractive to Frost remains to be seen as he is focused on VFL finals. 

The Lions need to add some defensive steel to their young backline after battling to restrain opposition forwards in 2016.

They conceded on average 18.1 marks inside 50 a game throughout the season, the worst rate in the competition.

Even allowing for the fact the team conceded the most inside 50s, it revealed aerial support was needed.

The Lions have promising youngsters in the back half with 19-year-old Harris Andrews an exceptional talent and 20-year-old Darcy Gardiner showing good signs.

Tom Cutler, 21, is also a great kick capable of breaking the lines.

However, the key position stocks are thin and the retirement of veteran Daniel Merrett has created an opportunity for a key defender.

Frost, who earned his only Brownlow vote for his performance on Anzac Day last year, is a popular figure at the Magpies and was on Collingwood's senior list this year.

Collingwood is yet to sign Nathan Brown who has attracted interest from North Melbourne, but will welcome back key position player Lachie Keeffe from suspension in December.

Brown's decision could impact on Frost's prospects at Collingwood. 

The Lions formally applied to the AFL for a priority pick on Friday and AFL chief executive Gill McLachlan has admitted they have a good case.

The Lions have not played finals since 2009 and have won just seven games in the past two seasons.