Ireland captain Paul O'Connell struggled to mask his disappointment after he said farewell to Test rugby in Dublin on a losing note.
Wales deservedly claimed a 16-10 World Cup warm-up success at the Aviva Stadium, built on flanker Justin Tipuric's first-half try and 11 points from the boot of full-back Leigh Halfpenny.
Ireland now complete their World Cup preparations against England at Twickenham next Saturday, and there is little doubt that they will require an improved display.
"There are a certain amount of things we wanted to improve on from the Scotland game, and we probably didn't do that. From our point of view that is disappointing," O'Connell said.
"There is no doubt about it that it's disappointing.
"There are certain things that we pride ourselves on, and we didn't do a whole lot of those very well today, with discipline being one of them.
"It's very hard to play as well as you would like in your first start of the season. I really appreciated the reception I got from the crowd today. I was just a little bit embarrassed that we lost the game.
"The penalty count is a big thing. Wales are a big side, and we gave them a few good cracks at us on five-metre drives, and we gave Leigh Halfpenny a lot of kicks at goal.
"I thought some of the penalties were tough and difficult to take, but at the same time, you can't blame that on a 15-6 penalty count against you.
"Victory is always important - that is what underpins everything we do.
"When we get a certain amount of things right in our game, it always puts us in a good place to win the match. Until we start putting those things in place, we don't stand a chance of winning, especially those big games against big teams."
Ireland suffered an injury scare midway through the second half when wing Keith Earls was carried off, but head coach Joe Schmidt gave an initial positive fitness bulletin.
"Keith just got caught with his head on the wrong side of the tackle. He was totally lucid in the changing rooms and remembered his involvements in the game, so they are promising signs, " Schmidt said.
"He will follow the concussion protocols.
"To be honest, it is a little bit of deja vu. We conceded a lot of penalties at the Millennium Stadium during the Six Nations last season, and I think we were six-nil down on penalties today when we were 10-0 down on the scoreboard.
"You can't give Leigh Halfpenny goalkicking opportunities, because he is too good at it. You can't give a team the quality of Wales the opportunity to enter into your defensive zone, because they will make you pay for it.
"I said to the players in the changing room it's going to be very tough next week.
"They (England) are going to look to rebound from a slip-up in France, and they are going to bring a really physical performance to Twickenham to lay down a marker prior to the World Cup, and we are going to have to walk in there and man-up and do the best we can."
Wales head coach Warren Gatland reported that centre Jamie Roberts and lock Alun-Wyn Jones both suffered bumps and bruises during what was a high-octane clash, considering its' pre-tournament warm-up status.
"Alun-Wyn was precautionary really," Gatland said.
"We made a decision it wasn't worth him playing on and potentially picking up a tournament-ending injury, so it was just a case of getting him off the field and seeing if we could cope with that for the last few minutes, and we did that.
"Jamie just got a knock in the ribs. Hopefully, we are relatively unscathed, but those kind of things you don't really find out until the next morning."
Wales' victory took them above England in the official world rankings four weeks before the countries clash in a pivotal World Cup game at Twickenham, but Gatland dismissed any relevance.
"It doesn make any difference to us," he added.
"We came here to play against the number two team in the world. We are the only side that have beaten Ireland in the last 15 games. We weren't speaking about the rankings or whatever.
"We just know how close teams can be. The way the game is at the moment, you can win by 15 or 20 points and the team you are playing against change their game-plan and do things differently and you can lose by the same margin the following week.
"So it (rankings) doesn't mean anything. It's just bragging rights, that's all it is."
Reflecting on his team's display - Wales became the first team to beat Ireland in Dublin since world champions New Zealand toppled them in November 2013 - Gatland said: "It was a good performance.
"We knew the whole focus of this campaign so far in preparation was to win a big game away from home, because we've got to go to Twickenham for a couple of big games (in the World Cup).
"So to beat the number two team in the world was good.
"I know it was close at the end. Ireland could have won it, and that would have been heartbreaking for us, but potentially it could have been a lot more comfortable for us as well."