Nathan van Berlo will again be sidelined this weekend for Adelaide's cut-throat semi-final clash with Collingwood at the MCG after the midfielder pulled out of the team's main training session on Wednesday.

Van Berlo missed only one match in the home-and-away season but cruelly picked up the injury in the Crows' final-round slaughter of Carlton which ruled him out of last week's elimination final against Essendon as well.

But in better news for Adelaide, defender Nathan Bock and tagger Robert Shirley completed the closed session without incident.

Crows assistant coach Todd Viney said the loss of van Berlo was a blow for the side.

"He's one of the leaders of the team and he's got a good finals record so we we're hoping he'd be right but you never quite know with backs and he's pulled up tight in the middle of training so we didn't want to push him any further than that," Viney said.

"He did the full warm-up, a couple of drills and then just felt like he was stiffening up. I guess at that point we knew he was in trouble, we didn't push him any further and hopefully he can get himself right for next week."

There's a feeling of deja vu surrounding the strength of Bock's heel with the 2008 All-Australian completing the team's main training session last week only to pull up sore the next day.

But Viney said the club and the 26-year-old were more optimistic about his powers of recovery and chances of playing this time around.

"Nathan thinks he's pulled up a lot better today and got through the whole training and probably looked better than he did last week. He didn't look like he had the same sort of limp as he did last week," Viney said.

"I thought he was alright skill wise, last week he was pretty good too."

Adelaide's match committee will meet on Wednesday night with Bock's immediate future sure to be on top of its agenda.

He might be one of the club's best players but during his time on the sidelines the Crows have been in scintillating form and the Magpies forward line doesn't look as big or as imposing as some of the other finalists, with Travis Cloke, Alan Didak, Leon Davis and Paul Medhurst all down on form last week and Anthony Rocca injuring himself.

"The match committee have got to make some decisions with Bocky, whether we play him or whether he goes to Woodville-West Torrens and plays a game (in the SANFL)," Viney said.

"Or we don't do that and we give him another full week of training, it's such a hard decision."

Viney, a former Hawthorn assistant coach, knows all too well the risks involved when selecting players who are under injury clouds and he said the Hawks faced similar dilemmas heading into the 2008 Grand Final.

"The one that was in my mind was Trent Croad last year. Completely different sort of injury but we thought we'd get through with Trent and he didn't get through. Five minutes into, I think it might have been the second quarter, he breaks down and we are one down so it certainly does stretch you if it doesn't come off for you," said Viney of last year's premiership decider which also saw Hawthorn lose Clinton Young before half-time.

"But there would be numerous stories of players that have gone into finals series or games injured and got through."

The Bock debate won't be the only match committee discussion with Shirley's availability another point of discussion.

In Round 19, Adelaide controlled Dane Swan's influence but a free Alan Didak swung the result Collingwood's way.

Viney admitted Michael Doughty and Brent Reilly were other players capable of performing the go-with role.

"They do have some star players, some important players to the way they play but we are not a team that goes in with five or six tags," he said.

"We've been pretty steady with one for most of the year so you have lots of contingencies ... we'll just have to prioritize."

Meanwhile, Viney said comparisons could be drawn between Hawthorn's charge towards the 2008 premiership and Adelaide's current finals campaign.

"I guess you say Adelaide has some fantastic momentum at the moment. There are similarities in that regard," he said.

"Completely different in teams and where they are at but I guess with the way we are playing at the moment, playing really exciting brand of footy, kicking a lot of goals over the last couple of weeks, defensively we've been pretty good so there are similarities between the group(s)."