Dense fog has forced the postponement of Friday night's Magners League match between Llanelli Scarlets and Newport Gwent Dragons at Stradey Park.
Referee Nigel Owens called the game off after a 1600 GMT pitch inspection.
Scarlets chief executive Stuart Gallacher said thick fog at the ground meant the posts were not visible from the halfway line.
"Nigel's view was that it wasn't safe and the weather is certainly not getting any better," said Gallacher.
"The temperature is dropping and we wanted to call it off as soon as we could so people could change their travel arrangements.
"We are very, very disappointed. It was a Christmas fixture we were all looking forward to and unfortunately the fog has beaten us."
The match, which was due to be televised on BBC Two Wales, was the Scarlets' only home fixture over the Christmas period, and Gallacher said its postponement was a major financial blow.
He suggested the match could be rescheduled for 24 March - the date of the EDF Energy Cup semi-finals - where the Scarlets and Dragons have free weekends.