The Principality Stadium roof will be partly open for today's game between Wales and Australia. It's due to a mechanical fault and comes on a day there is Met Office weather warning in place for rain in Cardiff.
A statement from the Welsh Rugby Union said: "The computer software which controls the roof mechanism has encountered a mechanical fault which could take several hours to repair and therefore cannot be resolved before kick-off. For the reason, the roof will remain with its current three-metre gap for this afternoon's match."
The retractable stadium roof has been fully closed for Wales' first three autumn Tests against New Zealand, Argentina and Georgia.
The Met Office weather warning covers much of south Wales, including Cardiff, and is in place from 2pm today (Saturday) to 6am on Sunday.
The Met Office said "rain, heavy at times, is likely to cause some disruption on Saturday afternoon and night", with spray and flooding on roads probable, public transport journeys facing disruption and flooding of homes and businesses a possibility.
