Tottenham Hotspur manager Ange Postecoglou expressed his disgust following his side's "disappointing" defending in their 3-2 loss to North London rivals Arsenal.
The Lilywhites conceded three goals in the first 38 minutes of the match at the Tottenham Hotspur Stadium, as Arsenal bolstered their Premier League title bid.
The thriller in North London got off to a rapid start after Pierre-Emile Højbjerg headed the ball into his own goal to give the Gunners an early advantage.
Spurs nearly replied soon after as Christian Romero's header was narrowly denied by the post.
Micky Van de Ven thought he etched his name onto the scoresheet after he latched onto a loose ball inside the arsenal box before he fired home.
However, his goal was ruled out following a VAR check which deemed him offside by millimetres.
Spurs' afternoon soon went from bad to worse.
Dejan Kulusevski and James Maddison went down inside the box and sought a penalty but Michael Oliver soon waved them away.
Seconds later, Bukayo Saka was picked out with acres of space on the left flank, before he cut in from the right and unleashed a shot into the bottom corner.
Tottenham's recurring set-piece woes haunted them again as Kai Havertz headed the ball home sending Postecoglou's side into the break 3-0 down.
Saka forced Guglielmo Vicario into pulling off a fine save to deny Mikel Arteta's side a fourth, early in the second half.
A mistake from David Raya handed the Lilywhites a lifeline in the match.
He intended to clear the ball up the pitch but instead sliced an effort into the path of Romero who slotted the ball home to finally grab a goal back for the hosts.
Another Arsenal mistake gifted Spurs the opportunity to score.
Declan Rice mistimed his clearance of a loose ball inside the box which led to him kicking the inside of Ben Davies' groin resulting in a clear penalty for the home side.
Spurs star Son Heung-Min did not mess around and rifled the ball into the top-left corner to pull it back to 3-2.
Despite a spirited second-half performance from the Lilywhites, their bitter rivals walked away with all three points.
On Tottenham's first-half performance
In the post-match conference, Postecoglou claimed that his side allowed Arsenal through on goal far too easily throughout the first half and that lost them the game.
He commented: "It was disappointing.
"We allowed way too easy access to our goal three or four times, and they scored three times in the first half.
"They're a good side and they will punish you.
"It is not acceptable at this level and we paid the price for it."
Postecoglou on the Van de Ven disallowed goals
The Australian could not resist commenting on modern refereeing following the controversial decision to chalk off Van de Ven's goal.
He claimed: "The games are not refereed in the stadium.
"I don't celebrate goals anymore.
"I wait until the referees down the road make the decision."
However, he claimed that his side was not at the same level as their opponents despite not having the rub of the green.
The Australian stated: "We didn't feel hard done by today.
"I want us to get to the next level and the next level has fine margins.
"We're not there yet and that's on me to make sure we get there."
Postecoglou on his side's second-half performance.
Despite fuming over his team's first-half performance, the Australian praised his team's mentality and display in the second half.
He said: "We showed resilience and fought back, but we had to because there was no other choice.
"We couldn't come out in the second half and not give our supporters a little bit of hope.
"But, we are still not as resilient as we can be, particularly in transitions and set pieces."
Postecoglou on what needs fixing
The manager highlighted that many things need to be changed in his team's performance if they are going to compete at the top.
He claimed: "There are a lot of areas of concern right now.
"We've got to fix a lot of things.
"Sometimes you need to feel the pain and realise you need to do things differently next time.
"If you feel the pain and don't change, then I have to do something about it.
"I don't want blind belief. I don't want people just doing what I'm telling them to do."
"I want people that have conviction.
"We're not there yet but that's okay. We've just started this process.
"I understand some people will be in, some people won't. Some people will embrace it, some others won't."