Northern Ireland boss Michael O'Neill was stunned by the penalty decision that ended hopes of claiming a point in the World Cup qualifier against Russia.
NI trailed 1-0 in the group opener in Moscow with 12 minuters left when a spot-kick was awarded against Craig Cathcart and Roman Shirokov converted.
"At 1-0 we were well in the game and the penalty, a very soft penalty, killed the game for us," said O'Neill.
"I was very surprised - there looked to be no contact whatsoever."
Blackpool defender Cathcart did not appear to make any meaningful contact with Alexander Kokorin but Spanish referee Antonio Miguel Mateu Lahoz pointed to the spot.
"My initial reaction was that the referee had booked the striker for a theatrical fall," added O'Neill
"The referee was very fussy towards us throughout the night. The lads didn't deserve that, they deserved to stay in the game."
Despite defeat, O'Neill believes his side showed all the core values he was looking for at the start of the new campaign.
"Russia are a very strong team, we knew that from the analysis we did," he said.
"The team is very similar to the team under Dick Advocaat and we knew they would cause us problems.
"We could have been better in possession, the players know that, but I would rather focus on positives - the discipline, the shape and the work-rate of the team was fantastic."
Northern Ireland defender Jonny Evans injured an ankle just before the break but he completed the game and O'Neill is confident he will be fit for Tuesday night's qualifier against Luxembourg at Windsor Park.