Caretaker boss Danny Coyne bemoaned a lack of discipline from Shrewsbury after Ryan McGivern's red card cost them in a 3-2 derby defeat at Walsall.
The managerless Shrews, second bottom in Sky Bet League One, twice came from behind to level as Oliver Lancashire's header and Junior Brown's strike cancelled out Amadou Bakayoko's first Walsall league goal and a Kieron Morris effort.
In a dramatic 10 minutes after Brown levelled at 2-2, Town were denied both a goal and a penalty by the offside flag and then saw McGivern dismissed for a second yellow card after clashing with Bakayoko.
The 10 men seemed to have held on but Erhun Oztumer's corner crept in directly at Town keeper Jayson Leutwiler's near post to hand Walsall back-to-back league wins for the first time this season.
Coyne said: "It is devastating to lose like that when the lads have battled like that after going down to 10 men.
"We should have scored a few goals and then we get done with a goal like that at the end after being on top in the second half.
"I have spoken to Ryan, he has apologised to the lads.
"He got caught up in things. He knows what he has done. That doesn't help when we are sat there at the end of the game but we've got to start learning from things like that.
"There was a lack of discipline there. That's what we need to stop really.
"The lads were getting frustrated with some decisions given. We had a penalty given but the linesman flagged for offside.
"But when decisions go against you, you've got to deal with it, be composed and we can't do things like that especially when you are on a yellow card."
Walsall also ended the game with 10 men as Bakayoko received a second yellow for celebrating Oztumer's winner with the fans.
But that couldn't take the gloss off the victory for Saddlers boss Jon Whitney, who said: "It was a proper derby.
"Sometimes it's not about winning comfortably and playing great football - sometimes you just have to win a little bit ugly.
"It's three wins now on the bounce and one defeat in seven.
"I thought we deserved the win. We didn't go chasing it and go direct. We kept playing our football and we created chances."
Whitney had few complaints about his striker's sending-off, admitting: "I think Ama jumped into the crowd. It's a mistake and a bit of naivety from him.
"I'm sure in hindsight if he could go back he wouldn't do it. But it was the emotion of the goal. It's a bit harsh because you want to celebrate goals but they are the rules.
"I thought their red card was harsh on Ryan McGivern as well - I know he's put his hands up but referees in my day would have said 'be careful, next time I'll send you off'."