Worcester boss Mike Ruddock admitted that the dismissal of Tom Wood had been the crucial moment as his Warriors suffered a 37-13 defeat to Bath Rugby in the Guinness Premiership.
Flanker Wood was sent off after collecting a second yellow card with 20 minutes left at the Recreation Ground as Warriors were reduced to 13 men with Chris Latham already harshly yellow carded.
Bath proceeded to score three of their five tries afterwards to run out winners and Ruddock admitted his side had learnt a harsh lesson.
"Tom let his frustrations boil over, he has apologised to the team in the dressing room and unfortunately that was the critical moment," said Ruddock.
"Up until then we were very competitive, it was 18-13 when he got sent off and we were in a good position near their line with a driving lineout. We were right in the game going into the critical period of the last 20 minutes.
"Tom reacted and I have spoken to the players who said he was pulled out of a maul and roughed up.
"He has learnt a harsh lesson. We lost him and were down to 13 men and so the avalanche began.
"We were in a position against Bath to win this game, there was only five points between us up until the point when we went down to 13 men.
"To concede a red while Latham was off was just something we were not going to be able to absorb. We absorbed the original yellow card from Tom Wood in the first half, but you can't keep soaking up pressure when you are down numbers.
"It is a shame because I thought we were in that game. Away from home, if you go into the last 20 minutes within one score of a team who are playing well, like Bath are at the moment, you have to fancy that you can give them a run for their money. A moment of madness let it go away from us."
Worcester started the game in positive mood as an early Willie Walker try gave them a 7-0 lead.
But Ruddock admitted decision making at key moments had again cost his side before the red card drama.
"I have been talking to my players for a while now about making better decisions, not just in our discipline to reduce our penalty count but when to run and kick," he said.
"We had scored a try and then Bath kicked off and it didn't go ten metres. We played a move that normally you would promote as we ran, but the last thing Bath wanted at that stage was to be drilled back in the corner after just conceding a try and then a poor kick off.
"The confidence is there, we know we can play, we are just not always making good decisions.
"Last week we gave away a number of penalties and Saracens never really looked like scoring a try against us. They had to score pretty much the try of the season from a turnover when we could have been under the posts," he added.
"Today we fell off two tackles and they scored twice in the first half - that was a major difference. That was about individual miss tackles.
"Against a side like Bath, who have hit a purple patch, once you are down to 13 men and you are trying to chase the game you are really up against it. Not many sides will come back from that.
Warriors will take a one-point advantage back to Sixways after a Niall Annett try on the stroke of full-time handed Dean Ryan's men victory in the first leg of the Greene King IPA Championship play-off final.