Crystal Palace captain Luka Milivojevic slammed his side's collapse at the hands of West Ham as "unacceptable" after their miserable run of form continued.
The visitors were on top at half-time on Saturday, leading courtesy of James McArthur's goal, while Milivojevic had struck the crossbar with a free-kick.
But Robert Snodgrass, Javier Hernandez and Felipe Anderson all scored as West Ham netted three times in a 17-minute blitz after the restart, the hosts ultimately prevailing in a thrilling 3-2 victory after Jeffrey Schlupp's late header for Palace.
Palace have only won one of their last 11 top-flight games and dropped to 16th, just two points clear of the bottom three, their weak submission angering Milivojevic.
"We started well and scored the first goal and had control… I hit the bar," he said. "The first half was something where we can take positives.
"In the second half they had possession. We tried to take control of the game and keep possession and play side by side but a lack of concentration and focus cost us.
"It is unacceptable to concede three goals in 30 minutes [17 minutes]. We pushed more to try and equalise but we can take big lessons from this game.
"Every single goal is a mistake of someone, I am not here to blame anyone. It is a collective game and we win and lose together. It is a big lesson I think, a very poor beginning to the second half.
"We didn't think when we attacked about what happens behind us and we left our defenders and they had some good counter attacks. We did not deserve to lose, they didn't create a lot of chances, we had a lack of concentration."
Palace boss Roy Hodgson, meanwhile, said: "We lost. I am not sure what assessment to make. It is no good scoring away from home if the opponents score three.
"The problem with football matches is you need to win them, we have ourselves a chance to win it but then you are 1-3 down and chasing the game which is always going to be difficult. There are no mugs playing at this level of football.
"We are disappointed as the free-kick [ahead of Hernandez's goal] was harsh for us, the yellow cards are disappointing and the two players will now be suspended for the next game, James Tomkins and Wilfried Zaha – to lose players with such good quality is disappointing."
It is the first time in two years West Ham have won three straight Premier League matches, and Manuel Pellegrini was particularly pleased to score three times in each of the victories, as he looks to establish an attacking style.
He told BBC Sport: "If you review the complete game Palace had three chances to score, and two they score. After that they didn't have any key options.
"They didn't score from a set piece all season but today they did. In the second half we started with more time and with the options to score and we scored three goals.
"It is the third game in a row where we score three goals and that reflects what we are trying to do.
"Every game is different, we concede two goals from a set piece - but I hope we will be more concentrated [in the future]. We were so bad to start with, we were playing too fast. It is very difficult to recover but we must continue to try.
"I always say to the player we must have a winning mentality. It really was a beautiful [third] goal - Felipe [Anderson] can at any moment decide the game."