Ireland head coach Joe Schmidt reluctantly accepted the decision that cost his side the chance to score a potentially match-saving try in their 22-9 Six Nations defeat to Wales on Friday.
Trailing 15-9, an Irish maul worked its way towards the line and a score that - if converted - would have sent the visitors in front in Cardiff.
However, referee Wayne Barnes blew for an infringement by Robbie Henshaw, who joined the maul ahead of the ball.
Though costly to his team, Schmidt - who did question the yellow card shown to Jonathan Sexton earlier in the game - had few complaints about the referee during his post-match interview.
"Wayne Barnes was on the spot. You can't join the maul in front of the ball," he told BBC Sport.
"Did he have a material effect? I don't know because I think if Robbie hadn't entered the maul we might have scored anyway.
"I thought we really got some good pressure on.
"I think it was tough when we conceded 10 points in the 10 minutes of the yellow card, and I think that was probably tougher [the decision to sin bin Sexton]. I can see Robbie's decision pretty clearly.
"Once you get behind against a Welsh team that are under pressure, that are tenacious, it's hard to build your way back in.
"There were a number of things that we've got to be better at and that's an incredible frustration."
Captain Rory Best added: "We're very disappointed. We came here expecting to win this game to keep everything alive and then I think we're just very frustrated with the mistakes that we made.
"Credit to Wales. They played very well as we knew they would because they're a quality side.
"But we made too many errors to win a game in the Six Nations away from home."
Defeat for Ireland all but rules them out of the running for the Six Nations title, with England now able to wrap up the championship by beating Scotland on Saturday.