Airdrie manager Ian Murray says goalkeeper Max Currie knows he had to deal with the situation that led to the winner in Montrose's 1-0 win over his team - and Celtic loanee Brody Paterson isn't to blame.
The 21-year-old looped a pass over the stopper and allowed Craig Johnstone to nip in and score during the Championship play-off semi-final first leg.
It leaves the New Broomhill side trailing heading into Saturday's return leg after a tight affair away from home.
There were chances for Airdrie too and Dylan Easton cracked the post with one of their better opportunities.
But Murray - who's side ended this year's League One campaign 20 games unbeaten - says a mistake ultimately cost them.
He said: "We can't hide from the fact it's an individual error. There's a lack of domination in an area where they should be. It's bread and butter stuff.
"We are disappointed with the goal and for the player involved in it. We had to regroup. I think the goalkeeper has to take the ball. Brody is looking for the goalkeeper.
"Max knows that and he's made a few good saves himself. He has done superbly for us this season but it's fine margins. We have missed fantastic opportunities we have to score in these ties."
The Diamonds boss knows the tie is still within their grasp but doesn't believe it's a great result for his team heading into that crucial clash.
Murray added: "These high-pressure games, you put so much of that on yourself. We couldn't come out of here 2-0 down.
"That would give us an uphill task so the next goal if there was one had to be us.
"The tie is within our grasp but it's a bad result as we wanted to win. We wanted out of here with a draw, minimum."
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