MELBOURNE has suffered a major blow with star Clayton Oliver to be sidelined for another month through injury.

The star onballer failed to finish a training session on Wednesday and was seen in a heated and lengthy discussion with a Demons staff member on the Casey Fields oval.

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The Demons issued a media release on Thursday, saying he has had further hamstring discomfort.

"What we have experienced so far is that Clayton can comfortably achieve 90 per cent of his running capacity, but as we saw yesterday, he is unable to get to full speed to pass his minimum training markers," said Melbourne football boss Alan Richardson. 

"This suggests that, due to the discomfort Clayton felt during his run throughs, further recovery time is required. At this stage, we expect this will be three to four weeks."

Oliver has been sidelined for six weeks with hamstring issues and a nasty infected blister, and the midfielder maestro had been pushing for a return in Saturday night's match against St Kilda.

"Clayton has a complex hamstring injury, due to the fact that the injury is located where the muscle attaches to the tendon, and to further complicate that, there is injury to two separate hamstring muscles," Richardson said.

"There is no doubt that Clayton's recovery has been complicated by the week he was required to spend immobile in hospital.

"The club will continue to explore all treatment options for Clayton, but as with all players we won't be taking any risks with his return-to-play timelines."

Melbourne is coming off an upset loss to GWS and has won only two of its last six games.