A waterlogged pitch at Rodney Parade has forced the postponement of Friday night's Pro12 match between Newport Gwent Dragons and Cardiff Blues.
Torrential rain on Friday afternoon resulted in significant surface water on the pitch, with the in-goal area on one side completely submerged.
And despite the desperate efforts of the ground staff, referee Nigel Owens decided the conditions were unsafe.
A full house had been expected for the highly anticipated derby match.
A number of Wales' World Cup stars were set to play for the first time since returning from New Zealand, and the Dragons were hoping to celebrate the official opening of a new stand.
Owens proposed a delayed kick-off of 2000 GMT to give the ground staff more time to clear the water, but the conditions remained unplayable.
"I'm extremely disappointed," said Dragons coach Darren Edwards. "This was going to be a great night for Dragons rugby.
"You can see the spirit we've got here, we've tried so hard to get the game on. People really wanted to see a spectacle and I'm really disappointed for them.
"I pushed the kick-off back as far as possible and credit to the Blues they accepted that. But safety does come first."
Blues coach Gareth Baber added: "They've worked really hard to get the game on. Obviously we wanted to get the game on but we've got to be careful in these situations."
Newport Gwent Dragons: Martyn Thomas; Tonderai Chavhanga, Adam Hughes, Ashley Smith (capt), Aled Brew; Jason Tovey, Wayne Evans; Phil Price, Rhys Buckley, Dan Way, Adam Jones, Scott Morgan, Andrew Coombs, Lewis Evans, Gavin Thomas.
Replacements: Lloyd Burns, Nathan Williams, Nathan Buck, Rob Sidoli, Tom Brown, Joe Bedford, Lewis Robling, Steffan Jones.
Cardiff Blues: Chris Czekaj; Alex Cuthbert, Casey Laulala, Jamie Roberts, Tom James; Dan Parks, Richie Rees; Gethin Jenkins, Rhys Thomas (capt), Taufaao Filise, Bradley Davies, James Down, Michael Paterson, Xavier Rush, Josh Navidi.
Replacements: Ryan Tyrrell, John Yapp / Sam Hobbs, Scott Andrews, Paul Tito, Ma'ama Molitika, Lloyd Williams, Ceri Sweeney, Gavin Evans.