Nigel Worthington accused his Northern Ireland side of lacking passion as they suffered a shock defeat against Latvia in a Euro 2008 qualifier.
An own-goal from stand-skipper Chris Baird after 56 minutes condemned the province to their first defeat in seven matches.
It also raises serious questions about their ability to qualify for a major championship for the first time in 21 years.
Worthington, in his second game in charge, could hardly contain his anger after seeing his side lose to a team that had lost seven matches in a row, including friendlies.
'There was not enough urgency or passion in our performance,'' said the Northern Ireland boss.
'That was disappointing and frustrating. We have not produced the goods on the night and let ourselves down.
'No matter what tactics or personel you pick if you do not get the basics right, you are not entitled to win the game.
'We were less than average. There was not enough quality on the night.
'It is one of those situations we have to try and get to the bottom off. Things have got be learned.''
Worthington is threatening to make wholsesale changes for the next qualifier in Iceland on Wednesday.
He said: 'I could change 11 players after that performance. There were not too many clever displays to warrant someone being an automatic choice.
'I will wait and see in the next few days who I think is going is going to give his all in Iceland.''
David Healy rarely looked likely to improve his 11-goal tally in the campaign but Worthington added: 'If you give him that type of service he is never going to score.''
The winner came when Andrejs Rubins skipped away from Sammy Clingan and found Maris Verpakovskis who delivered the ball into the area.
Baird got his bearings wrong and only succeeded in beating his own goalkeeper, Maik Taylor.
Worthington said: 'Chris will have to get over it, sooner rather than later. He is a professional - that's what you do.
'All the players like Chris are hugely disappointed at the way we played.
'But my main concern was the way we performed. We were not good enough.
'Latvia were neat and tidy. They did the simple things well. We were a million miles away from where we want to be.''