Melbourne coach Paul Roos has backed the AFL pre-season format as the minimum needed to adequately prepare players for the season proper.
Season-ending knee injuries to West Coast's Eric Mackenzie and young Bulldog Tom Liberatore renewed debate about the value of the practice games.
But Roos said the current NAB Challenge system - a pared-back version of the old NAB Cup - was a vital part of the calendar.
"You just couldn't possibly go straight into round one," Roos said on Tuesday.
"You have to have a form of conditioning. We're probably at the minimum level now ... I don't think you can go from nothing to playing a game - the jump would be just too dramatic, the injury rate would be enormous and the standard of footy would be ordinary.
"You don't like to see any players get injured, but that's just the reality of the game."
Those injuries occurred after Demon youngster Christian Petracca also suffered a season-ending ruptured anterior cruciate ligament - the same injury as Mackenzie and Liberatore - in training last month.
The 19-year-old initially harboured ambitions of returning to play this year after undergoing his knee reconstruction, but Roos would not hear of it.
"The first thing he said to me was that the doc told him he could play in four or five months," Roos said.
"I told him that the coach said you can't - I've overruled the doctor."
The Demons kick off their NAB Challenge series against Fremantle in Perth on Thursday night, with Roos naming a strong squad including Nathan Jones, former Collingwood star Heritier Lumumba and Chris Dawes.
But midfielder Jack Viney was ruled out of the trip after suffering a head knock during Tuesday's training session.
The line-up for Thursday also features young forward Jesse Hogan, whose much-anticipated debut season last year was ruined by a serious back injury.
"It's exciting for me too because I haven't seen him play (much)," Roos said.
"Fortunately or unfortunately we've had early draft picks and they always seem to bring some hype.
"(But) we're expecting him to play his role, be in good form in the NAB Challenge and hopefully get a game in round one."
In other injury news, former Crow Bernie Vince is still in the frame for round one despite a setback with a hamstring injury, but Jack Trengove remains out indefinitely despite progress in his recovery from a foot stress fracture.
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