St Mirren boss Jim Goodwin claimed referee Steven McLean cost his side dear in Perth, as St Johnstone triumphed 1-0.
Goodwin insisted the official got two key calls wrong as a Chris Kane strike separated the sides in a dour affair.
Buddies midfielder Cammy MacPherson was sent off for a second yellow card nine minutes after Kane's crucial strike.
But Goodwin insisted the foul on Israeli striker Guy Melamed did not merit a second caution.
And he was adamant the ball had struck Melamed's arm in the build-up to Kane's 46th-minute winner.
"I hate talking about referees, but Joe Shaughnessy headed the ball on to Melamed's arm, which was in an unnatural position way above his head," said Goodwin.
"You'd be screaming for a penalty if that was a defender in the box, so why Steven McLean didn't give it is beyond me.
"The sending off is another poor decision. The first yellow was borderline, Cammy got plenty on the ball.
"The second one is a mistake. Cammy clearly won the ball but for whatever reason it was deemed another yellow card.
"We lost the game to two poor decisions."
St Johnstone boss Callum Davidson was just relieved to end a 10-game wait for a win.
"I thought the first half was a real tight game," he said. "Guy had the best chance of the half that he probably should have put away, but apart from that there wasn't a lot in it.
"I asked the players for a bit more energy at half-time and we got the early goal. Once we did that and they got a man sent off I didn't think we were good enough. But I'm just delighted to get the win.
"I thought we defended really well and put our bodies on the line as soon as one of their players got into our box.
"The three points are so important.
"When you haven't won in a while it can sometimes be difficult to get over that line. I didn't think we were good enough on the ball in the second half and we allowed them to get into certain areas, but I would say we defended very well."
