UNBEATEN Melbourne will use Thursday's main training session to determine whether Harrison Petty or Michael Hibberd replace Steven May in Sunday's line-up to face Hawthorn.

May will be sidelined for at least the next fortnight after sustaining concussion in a nasty incident where he suffered a fractured eye socket against Geelong last week. 

The Demons will need to decide who partners Jake Lever and Adam Tomlinson in defence against a Hawks forward line likely to include talls Jacob Koschitzke and Tim O'Brien after Mitch Lewis' suspension. 

"We've looked at that pretty closely, we've got Harrison Petty and Michael Hibberd and both have pushed their claims incredibly strongly," Goodwin said on Thursday morning.

"We'll assess that at training today, but things we need to take into account when we make those decisions are whether we want to play the three talls in defence or we want to go a little bit smaller and get more run and carry off our back half." 

Hibberd has been an emergency for the past three weeks after an interrupted pre-season with an ankle injury, while Petty has impressed as a key defender as VFL level. 

Goodwin praised the job Tomlinson did on Coleman medallist Tom Hawkins after half-time last week to allow Lever to continue "playing the best footy he's played at Melbourne". 

Key forwards Sam Weideman and Ben Brown will play a full game for Casey against Box Hill on Sunday after restricted minutes last week in their respective returns from injury. 

Goodwin said the pair would then become available for AFL selection but an immediate recall against Richmond in round six wasn't a given. 

"Ben played a half and Sam played three quarters," Goodwin said of their games last week.

"Both will play a full game this week and speaking to our fitness staff, post this week they'll both be available for selection so that puts us in a really good position. 

"When it gets to that point it really comes down to performance. We've spoken to those two guys, whether that's an extra two or three weeks but we want to get them in really good form to play AFL footy, how long that takes, we're not too sure."

Goodwin also confirmed midfielder James Jordon would retain his spot to face the Hawks after playing 56 per cent of match time last week in a different role following May's injury as Angus Brayshaw played minutes in defence. 

Meantime, Goodwin insisted he never thought recently re-signed midfielder Clayton Oliver would leave despite rival clubs thinking he was gettable last year. 

"I think it's just brilliant for the footy club," Goodwin said of Oliver's two-year extension. 

"Clayton brings a lot of passion and energy to our footy club and we've got a core group of players that want to play together and want to build something special together. 

"Clayton's one of those guys and there wasn't for one moment I thought Clayton was going to leave our footy club. Would other clubs be interested in Clayton? Of course they would be, but the reality is that Clayton's a Melbourne person and wants to be part of this footy club. 

"I've actually got zero interest about what takes place away from Melbourne. Whether he's met with someone or not it doesn't really interest me."