A major slip overnight has delayed the reopening of Haast Pass until at least Monday and three boulders the size of houses are threatening to cause further blockages.
State Highway 6 - the only land link between the West Coast and Otago - has been shut since Wednesday, after a 50 metre slip at an area called Diana Falls.
The Transport Agency says snow and heavy overnight rain brought down almost as much debris again, taking the work to clear the pass nearly back to square one.
The agency hopes a break in the weather on Saturday afternoon will allow a geotechnical engineer to see how much more slip material may have been destabilised.
Three huge boulders perched above the latest slip need to be assessed to find out if they became unstable in Friday night's slip.
State Highway 94 from the Lower Hollyford turnoff to Milford Sound is still blocked by avalanches and slips.