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 told Press Association Sport.
"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."
Representatives from the clubs and unions of all six main European nations were meeting in Paris on Saturday, as talks rumble on aimed at a solution to the long-term wrangling.
Slow progress is being made on setting up a pan-European club competition to be run by the Six Nations committee.
But the ever-present stumbling block of TV rights will again rear its head, with England's Aviva Premiership clubs sticking to their agreement with BT Sport that rivals Sky's existing claims.
Any progress in France must be tempered, of course, by the continued uncertainty surrounding the Heineken Cup, and organisers European Rugby Cup (ERC).
English clubs' governing body Premiership Rugby (PRL) has long since refused to accept a European competition ruled by ERC for next season.
ERC continue to hold board meetings, and, at the latest, refused to release overdue tournament appearance payments to the clubs, fearing liabilities should they be wound up at the end of the season.
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 you can, and you can't afford to lose that.
"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."