Ryan Giggs accused his Wales players of complacency after an embarrassing 1-0 defeat to Albania.
Wales are 42 places higher than Albania, in 60th, on the FIFA rankings and the hosts had lost 4-0 to Scotland on Saturday to suffer Nations League relegation.
But Bekim Balaj's 59th minute penalty condemned Wales to a shock 1-0 friendly defeat in Elbasan, handing Giggs' side a confidence blow before the 2020 European Championship qualifiers start in March.
"The performance was not good enough, we deserved what we got," said Wales boss Giggs, who has now lost five of his nine games in charge.
"We totally controlled the first half and we thought it was going to be easy. It's nothing to do with hard work or the ability of the players.
"Quite simply, it was concentration and complacency. We just turned up thinking we would win, someone would score the goal, someone would get us out of trouble."
Gareth Bale was sent on for the last half hour but the Real Madrid forward failed to turn the tide Wales' way.
And on a night when Chris Gunter made his 93rd appearance to become the most capped Welsh player of all time, Wales were on the wrong end of some dubious decisions from Macedonian referee Dejan Jakimovski.
Taulant Xhaka escaped a first half red card after appearing to move his head towards David Brooks and make contact with the Bournemouth forward.
Jakimovski then turned down strong Welsh appeals for a penalty at 1-0 after Harry Wilson fell under Migjen Basha's challenge.
But Giggs said: "We should have been out of sight by then so I don't want to put any blame on the referee.
"Sometimes you get bad decisions in football and you have to get on with it. Maybe in the future it's a learning curve because sometimes you go away from home in a hostile environment and you don't get the decisions.
"You have to still play your own game and not lose your concentration, which we did. Up until tonight I've been more than happy with the players, but sometimes you need these sorts of results to put things in context.
"Players are still learning about me, I'm still learning about the players. Generally this group of players have come back after a defeat and proved the critics wrong. It was a lesson that there are no easy games in international football, you can't take anything for granted and we'll learn from it in future."
Albania manager Christian Panucci had seemingly come into the game with his job hanging by a thread.
Some pre-match reports even suggested that former Italy defender Panucci had been sacked before the game.
"I won't be sacked and I won't resign," Panucci said after Albania's second win in nine games.
"I like to fight until the end. I won't abandon the ship when the sea is harsh. I'm happy with the victory. The boys played well, even though we suffered at key moments in the first half."
