Manager Brian Laws has confirmed that Graves `tweaked` his knee in Saturday's victory over Macclesfield Town.
Peter Beagrie meanwhile is certain to sit out as he battles to recover from a hamstring injury.
"He has been working hard to strengthen the hamstring and it is getting better," stated Laws on Beagrie's injury.
"But we will not put him back into the firing line again until we know he is going to be 100 per cent right and that is likley to be another fortnight away."