England's World Cup preparations would take a hit if there was no top-level European club competition next season, according to Jonny Wilkinson.
World Cup-winner Wilkinson has called on European rugby's authorities to find a solution to the continued Heineken Cup impasse, and fast.
The Toulon fly-half believes first-class European club rugby plays a vital part in the England team's development.
"It's a great competition and it brings so much to the game, and it would be a sad day indeed if there ceased to be European competition," Wilkinson said.
"Everyone's aware of that as they watch it on TV and see teams from across borders get stuck into high-level rugby.
"I'm sure everyone's intent on finding a solution. I think it's very important for England."
Shelving the politics to focus on the positive impact of European club competition, Wilkinson said the Heineken Cup helps top stars touch "world-class" level.
"I don't think you can talk about different levels between leagues and the Heineken Cup, because all the games are high level," he said.
"But European games are certainly different challenges to prepare for: that ability to prepare for a huge contest, to construct a game-plan, to get yourself ready for big games against teams you're not used to facing, staying in games under pressure, that's all part of being a professional at the highest level, and all part of learning to be world class.
"And learning what needs to be done to perform at the highest levels.
"Also it brings new atmospheres, new energies around stadiums that you don't always get.
"It creates a different buzz, it's unique, and we need it; it does huge amounts of positive things for rugby in all countries."