Chris Coleman felt his Wales side showed they could compete without Gareth Bale and Aaron Ramsey despite losing 3-2 to Holland in Cardiff.
Holland captain Arjen Robben produced a Dutch masterclass with a second-half brace as Wales fought back twice before eventually suffering only a second defeat in 11 games.
Wales' build-up for Euro 2016 started without key pair Bale and Ramsey, but Coleman said he saw enough signs to be encouraged after goals from Joe Ledley and Emyr Huws eventually proved irrelevant.
"It was a good exercise, they are a good team who have been criticised a lot (after failing to qualify for Euro 2016) but they are still have top-quality players," Wales manager Coleman said.
"We knew it would be tough and we always want to win, but we got a lot of other things out of the game.
"We were competitive. We used our full number of six subs and were still competitive.
"We scored two goals without Bale and Ramsey, which is a big thing when you look at who was getting the goals for us in the qualification campaign.
"We also didn't have Hal (Robson-Kanu) so we were without our front three from the campaign but I was delighted for Tom Lawrence.
"He is a very good player, he has improved and has done very well for us and George Williams is also back after nearly a year out.
"Ben Davies has not been in the first team at Tottenham, James Chester has not been playing at West Brom but Paul Dummett and Adam Henley have got caps.
"We are building and these lads need minutes if they are to come with us to France."
On the downside, Wales struggled defensively, especially after skipper Ashley Williams had been withdrawn at half-time.
They were unable to cope with Robben who had defied his Bayern Munich bosses to play and take his tally against Wales to four goals in three games.
"We saw in patches glimpses of frailty which we did not see in the campaign where we were rock solid," Coleman said.
"We were a little bit open and they had Robben who could open up any defence in that form.
"We have world-beaters who can win a game but we have to do the ugly business.
"We can play good football and create, but we have to defend for our lives or we do not get the result.
"We are not good enough to play 60-70 per cent against these sides.
"We cannot go on to pitch whenever we want, we have to be right on it to get a result."
Holland have now won all eight of their games against Wales, but coach Danny Blind felt his side should have had a more emphatic victory.
"We played a good game, we played as a team but we had some problems in the first period," Blind said.
"In the second half we should have scored four or five but the goals we conceded were a concern.
"It was a hard job to motivate them after we missed out on the Euros but the team were focused and put a lot of energy in the game.
"We play Germany on Tuesday and France and England in March, the big countries.
"So I hope the motivation is there. We need those games for (World Cup qualification) preparation."