Alan Archibald was left frustrated by Partick Thistle's inability to turn possession into points but believed his side were denied a penalty in the 3-0 defeat by St Mirren.
Jim Goodwin appeared to handle a Kallum Higginbotham shot minutes before the hosts had Stephen O'Donnell sent off.
"You could hear by the roar of the crowd how obvious it was was that it was a penalty," said Archibald.
"Decisions like that can turn games. It was a chance for us to make it 1-1."
Thistle are still chasing their first home win in the Premiership and are on a run of just one victory in eight games after a bright start to the campaign.
Archibald lamented his side's lack of cutting edge up front but reserved most of his displeasure for the officials.
"Jim Goodwin moves his arm to the side and blocks the ball going towards the goal," he explained.
"If that's not a penalty, I don't know what else is. The fourth official said he didn't think he moved his arm, but he'll be embarrassed.
"That's the way things are going for us at the moment, we're not getting the rub of the green.
"The boys put a lot into the game, especially in the first half, but we couldn't get the goal.
"They got their first from a set-play and that's a sore one to take.
"It's a pattern that we are falling into and we can't feel sorry for ourselves.
"It's all right having a lot of good play, but we need to be more clinical and we've got to keep clean sheets.
"It was another set-play that changed the game today.
"You've got a job to do when you go out on that pitch and you've got to do it."
Steven Thompson headed the visitors into a 15th-minute lead and thereafter St Mirren sat deep, content to hit on the counter.
O'Donnell's second booking came with 20 minutes remaining and was followed by a Conor Newton strike and a stoppage-time finish from Thompson.
On the dismissal of his right-back, Archibald said: "The second booking was on the halfway line and I think there were a lot of other similar fouls in the game that weren't cautioned.
"I think the referee gave it because it was on the break."