Richmond coach Damien Hardwick admits one of the AFL's worst defences will need a quick-fix from within after a huge setback for the man earmarked to strengthen it.

The Tigers' best defender Kelvin Moore faces at least another eight weeks on the sideline, and the prospect of surgery which could end his season altogether.

Moore has not played at all this season because of a hip injury.

The club had been insisting Moore was close to a return to bolster a defence which has leaked more goals this season than any other club bar newcomers Gold Coast.

Instead, Moore's season now looks in jeopardy after he was added to the club's long-term injury list on Thursday following less-than-promising scans this week.

"It's whether we look at further surgery or whether we give him some time off to get that right," Hardwick said.

"We've decided to go with the less invasive action of putting him out for some time rest-wise.

"Obviously the surgery's a secondary option but we'd prefer to get him back this year because he's such an important player to our back six.

"It's probably six weeks and we look how it's going from there, but we hope he's back up and training in three to four weeks."

Under AFL rules for players on the long-term injury list, Moore will be sidelined for a minimum of eight weeks.

It leaves the Tigers, who take on upwardly mobile Essendon in the annual Dreamtime At The 'G clash at the MCG on Saturday night, facing several more weeks at least of fielding an inexperienced defence.

The backline was ruthlessly exposed by the Western Bulldogs in a big loss last weekend to snap a three-match Tigers' winning streak.

Hardwick admitted his players had to learn how to defend in a hurry.

"Defence is a mindset rather than anything else. How quickly you flick between offence and defence is generally how good you become as a side.

"We're playing three to four teenagers down there who between them have only played 50 games, so it's a way to the future for us."

Moore's move to the long-term injury list allows the Tigers to promote a rookie list player to plug the gap.

But Hardwick admitted none of his current rookies had really staked a claim with their reserves form and no quick decision would be made.

"We've got a number of players going okay, but no one's setting the world on fire.

"The bait's there for whoever wants to grab it."

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