Kilmarnock manager Alex Dyer labelled his side "unprofessional" as they failed to capitalise on their man advantage before being beaten 1-0 at Hamilton on Saturday.
The visitors' prospects of winning the Ladbrokes Premiership clash were boosted in the 78th minute when substitute Mickel Miller was shown a second yellow card by referee Willie Collum for a foul on Chris Burke.
But Killie failed to grab the initiative and looked devoid of any creativity as Hamilton sealed a vital three points in their relegation battle courtesy of Marios Ogkmpoe's late penalty.
Dyer said: "It's easy for me to say 'we deserved more from the game'.
"We created lots of chances but if you're not clinical in front of goal then you'll get punished – which we did. I'm bitterly disappointed that we didn't come away with something.
"If you take any positives, it's that we are creating chances but I can't really take much from the game today. We were unprofessional, they go down to 10 men and we went a bit gung-ho, then just switched off at key moments.
"We should take three points because the opportunity was there and we haven't taken them. They scored with four or five minutes to go and we tried to get back in the game, but we couldn't."
The match looked destined for a stalemate until referee Collum adjudged that Kirk Broadfoot fouled Ogkmpoe.
Despite Killie goalkeeper Laurentiu Branescu's best efforts, the Greek striker converted his penalty and Dyer had few complaints with the decision.
"I didn't really see it. I tried to watch a video afterwards but it was blurry with the rain. It should never have came down to that. The referee gave it and we move on," Dyer added.
Hamilton have enjoyed a remarkable week in their bid to avoid relegation. They moved off the bottom with a stunning win against Rangers in midweek before leapfrogging St Mirren into 10th place courtesy of Ogkmpoe's penalty winner.
Brian Rice was delighted with his side's performance but the win came at a cost with Jamie Hamilton and Blair Alston joining a lengthy injury list after they had to be replaced in the first half.
Rice said: "Blair has hurt his groin, Jamie Hamilton has swollen glands but he completed a test before the match and felt OK.
"After 10 to 15 minutes of the match, I could see he wasn't right because he'd done a couple of things that he wouldn't normally do."