Craig Levein's men headed for Belgium today seeking an elixir against the Belgians, and after witnessing the latest bout of cursed luck during the 2-1 defeat in Cardiff, McGregor believes the national team are overdue a dollop of good fortune.
Bad enough that Steven Fletcher was unfairly deprived a goal on his international return, but added to the offside opener scored by Macedonia at Hampden and, most gallingly of all, Jan Rezek's penalty award for the Czech Republic that denied Scotland a place in the play-offs for Euro 2012, McGregor's sense of grievance is not unfounded.
"I don't think we deserved that result, I really don't," said the Besiktas goalkeeper.
"I have said it already and I will say it again, some of the decisions we have had to contend with are really hard to take and it was the same again on Friday night.
"I am not taking anything away from Wales and I know it sounds like sour grapes but it is true and you only have to look at some of the incidents.
"If you look back to the penalty for the Czechs at Hampden; that cost us a play-off place. It happened against Macedonia when their goalscorer [Nikolche Noveski] was offside and again on Friday night, when a perfectly good goal was chalked off.
"From where I was I saw the flag go up early so assumed it was offside. Then the referee gestured that the cross had gone over the byeline.
"We couldn't believe it when we saw the incident afterwards and saw that the ball was well in play and that Steven's header was absolutely fine.
"It makes it that much harder to take as at 2-0 down the game is over – no doubt about it. We were playing well and creating chances and the second goal would have killed Wales off.
"Instead, they get a soft penalty and arguably they should have been down to 10 men in the last 10 minutes."
Tomorrow's match gives Scotland an immediate chance to banish the Cardiff collapse.
Belgium showed their qualification credentials with a 3-0 win against Serbia in Belgrade but McGregor believes the sense of injustice and determination will provide sufficient inspiration to upset the odds.
"It is important to bounce back when you don't get a good result and it is especially so now," he said.
"Qualifying has become more difficult now, but we can't give up and we need to look forward to the Belgium game with belief that we can take something from them.
"It's hard to pinpoint what is going wrong. As the manager said, we are just one ingredient away from things going well."