Crewe boss David Artell admitted his side 'have been our own worst enemies' and 'mistakes have killed us' after Sunderland ran out comfortable 4-0 winners at Gresty Road.
The Black Cats climbed to second place in the League One table with a 4-0 win against the Railwaymen, with an own-goal from Terell Thomas setting them on their way before Ross Stewart scored twice and then substitute Leon Dajaku scored a brilliant individual goal.
But Artell was disappointed with the manner of the goals his side conceded.
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"I thought we were good for the first 20, 25 minute- right up until their first goal really," Artell told the club's official website.
"We were slicker and better in possession. We closed them down and forced them into mistakes and created some good chances.
"They had some chances too but we were matching them and then we concede two goals in a short space of time and then didn't handle the second half of the first half very well.
"We came out second half and we conceded two goals from two corners. One from their corner which was a tap in and a killer goal, and then one from our own corner when they hit us on the counter attack.
"We have conceded five goals from set plays in the last three matches and you cannot do that.
"We have been our own worst enemies and the mistakes have killed us.
"I thought the performance was better than at Fleetwood [at the weekend] by a long way and we kept going but you cannot give goals like that to anyone, never mind Sunderland.
"The goals flattened us and one led to another and we have got to get out of that habit.
"It needs addressing and we will work hard to do that."
Crewe remain next-to-bottom of the table having won just one of their 13 League games so far.
