Scotland manager Craig Levein expressed his anger after seeing his side denied what he felt was a legitimate goal in their 2-1 defeat to Wales at Cardiff City Stadium.
Having already provided the assist from which James Morrison put the Scots 1-0 up in the 27th minute, Steven Fletcher - back in the side for the first time in over two years - thought he had doubled their advantage in the second half when he headed in Charlie Adam's cross.
The effort was disallowed, though, with the delivery from Adam adjudged to have gone out of play - despite replays suggesting otherwise.
Gareth Bale subsequently equalised from the penalty spot in the 81st minute after it was deemed he had been fouled in the box by Shaun Maloney, and then rifled in a delightful winner with a minute of normal time remaining to leave Scotland with just two points from three games in World Cup Qualifying Group A.
Referring to the disallowed goal, Levein said: "You can understand my frustration.
"Everybody who watches it can make up their own mind about whether it was a good or poor decision by the officials.
"I can only relay my feelings, and I am extremely angry about this happening to us again.
"We have been subject to a couple of really poor decisions and it has a huge effect on our chances of qualifying."
He added: "With 10 minutes to go I just could not see us losing the match.
"Getting the second goal was always going to be crucial, though, because a 1-0 lead can be fragile, and so it proved.
"That second goal was so important for us, and I believe the officials made a serious error with the chalked-off goal that Steven Fletcher scored. That is very hard to take."
After they had lost their two opening Group A fixtures, Wales are now off the bottom and up to fourth, behind leaders Belgium and second-placed Croatia, who both have seven points, and Serbia, third on four points.
That will ease the heat on Dragons boss Chris Coleman, but it is only being turned up on Levein, whose fifth-placed team had already made a disappointing start to their campaign with home draws against Serbia and Macedonia - the new rock-bottom side - last month.
Asked how much pressure he felt he was under ahead of Tuesday's away clash with Belgium, Levein said: "Any time you take to the field for an international match, the pressure is exactly the same.
"I don't want to talk about 'what if this happens' or 'what if that happens'.
"The important thing now is that I do the job to the best of my ability and get the players up for Tuesday."