Joe Hart branded West Ham's late capitulation at Crystal Palace "unprofessional" and said it left his team-mates lost for words.
Hart was unable to stop Wilfried Zaha scoring a 97th-minute equaliser at Selhurst Park to complete a dramatic comeback and deny West Ham a morale-boosting victory.
Javier Hernandez and Andre Ayew had put the Hammers two up at half-time, but Luka Milivojevic converted a penalty early in the second period before Zaha's stoppage-time strike earned Palace a 2-2 draw.
Hart was unfortunate not to finish a victor. The England goalkeeper pulled off a string of excellent saves, including one with his finger-tips to keep out a James Tomkins header late on.
"I can't believe we've done that," Hart told the official club website. "I can't believe we've fought all the way to the end and then been so unprofessional at the end.
"It's a little bit speechless in the dressing room. No one does things on purpose in this team, but it's two points dropped - as simple as that.
"I hadn't switched off, but it was a good finish by Zaha, through legs, and I'm bitterly disappointed."
West Ham came under sustained pressure in the last 10 minutes, but they were naive too at the end.
"You've got to keep the ball in the corner, it's that simple, and you can't let people keep running through you and getting chances," Hart said.
"Today counts for a point, but that's about it. We learn simple things."
Zaha admitted Hart looked unbeatable, but his shot into the far corner ensured Palace avoided defeat for only the second time this season.
They remain bottom of the table, however, with West Ham just five points better off.
"It was beginning to look impossible to beat him," Zaha told the official club website. "We did in the end though and managed to get a very important point for us."
Zaha's goal was his second in three games as he continues to enjoy the new role further forward given to him by manager Roy Hodgson.
The 24-year-old says he also feels the extra weight of responsibility playing up front.
"I do at times feel that pressure from the stands and get nervous at times as maybe people expect too much from me," Zaha said.
"But I don't mind that and I take it on and do what I have to do for the team. In my current position in the team I know I don't make the normal striker runs, but it's been a bit easier because it gives you a bit more of a free role.
"It allows me to pick the ball up deeper from the midfielders and take on the centre-back and if I go past them it is just the goalkeeper and I have enjoyed it so far."
Palace visit Tottenham next weekend, while West Ham host to Liverpool.