Wales and France will play their RBS 6 Nations clash in Cardiff on Friday night with the Principality Stadium roof open.
The Welsh Rugby Union said in a statement that "a technical problem" had occurred on Friday morning, which meant the roof would stay open.
France, as the away team, had agreed earlier this week with Wales for the roof to be closed.
Weather conditions in the Welsh capital two hours before kick-off were cold and breezy, but dry.
The WRU's statement read: "The Principality Stadium roof will stay open for this evening's RBS 6 Nations clash between Wales and France.
"Both teams have been informed of the situation.
"A technical problem occurred early this morning and has not been able to be resolved despite engineers working on a solution throughout the day."
The malfunction will be a source of embarrassment for the WRU on such a showpiece occasion, with a capacity 74,500 crowd expected at the stadium.
Both teams went into the game with unbeaten records in this season's Six Nations, with the winners set to take top spot ahead of title rivals England tackling Ireland at Twickenham on Saturday.