EXCITING young Demon Jack Grimes is likely to miss Melbourne's clash against the Sydney Swans at Manuka Oval on Sunday.

Grimes is struggling with a back injury, a problem he had earlier in the year, with coach Dean Bailey almost ruling out the 2009 NAB AFL Rising Star nominee.

"He's had back issues earlier in the year and on the weekend he got a couple of knocks on the back and he's certainly pulled up pretty stiff,” Bailey said from Junction Oval on Wednesday.

“We'll see how he trains in our main session, but I'd say he'd probably be 50/50."

Ruckman Mark Jamar has already been ruled out with a quadriceps injury, which he sustained against Geelong at Skilled Stadium last Saturday. Jamar also missed rounds 12 and 13 with a quad problem.

Bailey said he was disappointed to lose the ruckman to the same injury as his form had been good.

"His hit-outs have been good and he's taken a few more contested marks around the ground and he's making some good decisions,” Bailey said.

"It's disappointing to get a soft-tissue [injury] at any stage, particularly this time of the year."

The loss of Jamar will give Paul Johnson a reprieve. The ruckman/forward played the opening 13 rounds, but has spent the past three matches in the VFL.

Bailey said the club’s other replacement ruck is not ready to return at AFL level yet.

"Young [Jake] Spencer hasn't really played enough games for Casey,” Bailey said. “It would have been a nice situation if Spencer had played some games in the VFL, to bring him up and give him some experience."

Another experienced Demon Paul Wheatley will also be sidelined for two weeks with a quadriceps injury.

"With soft-tissue injuries, they're more likely two than one week, just because of the nature and they're a kicking muscle as well," Bailey said.

"It's disappointing for Paul - it was the second last exercise we did [at our last training session before round 15]. It was a minor nick, but because it was in a similar area to where it was before, it adds an extra week to his rehab or his delayed comeback."

Despite some impressive recent form with Casey in the VFL, Bailey said rookie midfielder Jordie McKenzie was unlikely to gain a call-up this round.

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