Wales head coach Warren Gatland was left frustrated by referee George Clancy's interpretation at the breakdown, despite seeing his side move to within a win of another Grand Slam with a 24-3 Millennium Stadium victory over Italy.
Second-half tries from centre Jamie Roberts and wing Alex Cuthbert helped Wales to set up a shot at a third clean sweep in eight seasons against France next Saturday, while Leigh Halfpenny contributed 11 points with the boot and Rhys Priestland added a penalty.
"I thought there was a lot of intent by us but it was a bit frustrating because the flow of the game was not there," he said. "We were not allowed to get quick ball and the breakdown was a bit of a mess."
He added: "We will take the win but if a team has that much possession and territory and loses the penalty count 13-12 you have got to be frustrated about that. We weren't allowed to get the momentum going.
"It's probably just about trying to get the message through to referees, let's be positive to the team that is trying to play positively and let's reward them for that. I don't think everything has to be 100 per cent to the letter of the law because there is so much interpretation. That's why I am personally pretty frustrated because it was difficult for us.
"They came with a limited game and didn't allow us to function. That's what rugby is about and there is nothing illegal about doing it. You just hope that too many teams don't win by doing that."
Despite his frustrations Wales will face France at the Millennium Stadium looking to once again claim the crown of the best side in Europe.
For many of Gatland's young squad it will represent a first shot at a Grand Slam, but the New Zealander has every confidence that his players will be able to cope with the hype they will experience in the principality ahead of next weekend's meeting with the side who ended their World Cup ambitions in heartbreaking fashion last October.
"It won't be difficult for us to get through this week at all," he said. "The guys have got their heads on. These young players are just taking these things in their stride.
"The players are well aware about the huge amount of hype but I would like to think they are in a good place and that the Welsh public are pretty happy with them."