Gareth Bale says Wales must learn "the dark arts" after conceding a last-minute goal that saw them beaten 2-1 by Nations League opponents the Netherlands.
Wout Weghorst's diving header deep into stoppage time saw the Netherlands home, with the goal following an outstanding run by Frenkie de Jong.
Ryan Norrington-Davies had equalised for Wales just two minutes earlier, but they could find no way back after Weghorst struck.
"The boys who came in worked very hard to get the equaliser," Bale told S4C.
"Then to concede so early after that was gutting, but it's something we have to learn, maybe the dark arts of taking him (De Jong) down. We need to learn from this. They are a world-class team and we are in this A league now because we deserve to be testing ourselves against the best.
"I think if you are a tier below you get away with that at the end. You play the top teams, you don't do the things you need to do and you get punished. It's hard to take, but it is something we need to learn from. We are still a young team, and we have to learn from stuff like that and take it forward."
Norrington-Davies looked to have extended Wales' unbeaten home record when he struck his first Wales goal to cancel out Teun Koopmeiners' opener.
But Holland went straight up the pitch and Weghorst's superb header inflicted a first home defeat on Wales since November 2018, ending a run of 19 games unbeaten on Welsh soil.
Four days earlier Wales had qualified for their first World Cup for 64 years and this was definitely a case of after the Lord Mayor's show with the intensity of the occasion often resembling a friendly more than a competitive fixture.
Both teams fielded shadow sides - in Holland's case they made 11 changes from the side that had thumped Belgium 4-1 in their Nations League opener.
Bale won his 104th cap after being sent on for the final 13 minutes, but Wales slid to a second Nations League defeat following last week's setback in Poland.
Wales manager Robert Page said: "I am coming away disappointed that we haven't got at least a draw. We gave ourselves a great opportunity, then showed a little bit of naivety, but that is a lesson we have got to learn. I can't fault the effort of the players again. I am really proud of them for that performance against a very good Dutch team."