ADELAIDE has started contract talks with emerging ruckman Reilly O'Brien while still having interest in Collingwood's All Australian big man Brodie Grundy.

O'Brien's value is increasing with every game the 23-year-old plays and he continues to hold 198-game veteran Sam Jacobs out of the side.

Grundy is contracted to the Magpies until the end of 2020, but has reportedly put off talks about an extension until the end of the season.

Crows coach Don Pyke wouldn't be drawn on whether O'Brien's sudden rise had lessened the need for the Crows to go after South Australian product Grundy.

The Magpies would all but certainly demand two first-round draft picks – with one of those the prized Carlton selection that currently belongs to the Crows – as part of any deal for Grundy.

Grundy, as the most dominant ruckman in the competition and coming into his prime at age 25, would also command a salary of $1 million per season or more.

 "Let's deal with the known knowns," Pyke said on Wednesday.

"We've got a player who's performing strongly who we've got four or five years of development in that we want to keep at the footy club.

"That's the conversation at the moment.

"Everything else is, I don't know, out there, in the ether ... may happen, may not.

"We've got a guy right now that's doing a really good job for us that we want to re-sign."

O'Brien has played the past 11 games, taking his career total to 13 in his five seasons at the club after being taken with the ninth pick in the 2014 rookie draft.

He is coming off his most complete performance, racking up 54 hitouts, 19 disposals, seven inside 50s and six clearances in the Crows' 33-point win against Richmond – which called upon makeshift rucks Noah Balta and Mabior Chol - in round 13.

"He's going out there knowing 'I am an AFL ruckman, I am good enough at this level'," Pyke said.

"What (O'Brien) has done over the (past 11) weeks is give himself the belief that he's good enough to compete against the rucks in the AFL and hopefully have a long career.

"With Reilly, we want to re-contract him.

"That's part of the process we're going through at the moment."

The Crows will almost certainly be without utility Wayne Milera for Friday night's blockbuster with ladder leaders Geelong at GMHBA Stadium on Friday night.

Milera has a lower back injury and did limited training on Wednesday.

"He's had a bit of a sore back, which has restricted him a bit," Pyke said.

"He's probably unlikely at this stage."

That could open the door for Bryce Gibbs to return to the side.

"Bryce played some good, strong footy before the break and his name will come up for consideration," Pyke said.

"His attitude has been first class."

Pyke confirmed young forward Elliott Himmelberg was set to be the replacement for the injured Josh Jenkins.

The Crows (8-5) are aiming to win at Geelong for the first time since 2003.

Pyke got a first-hand look at the Cats (11-2) in their 11-point loss to Port Adelaide at Adelaide Oval last Saturday night.

"Port were really strong in the contest and they put good pressure on Geelong," Pyke said.

"That's a fundamental of how we want to play and it will be no different on Friday night."

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