Sam Allardyce bemoaned West Ham's habit of conceding late goals following Romelu Lukaku's stoppage-time winner in a 2-1 defeat to Everton on Saturday.
Lukaku found the net after Leon Osman had cancelled out Stewart Downing's opener - the Belgian having previously scored a last-gasp leveller in the return fixture.
West Ham have also dropped points courtesy of late goals against Tottenham, Leicester City and Stoke City since the beginning of 2015.
"Since the turn of the year, I think that's five in the last minute," said Allardyce. "Another bitter disappointment for us on the basis that it was a very entertaining game in which we had our noses in front and didn't maintain the correct amount of defending... to make sure we made life more difficult for Everton to score.
"Trying to be more and more creative to trying and score another goal, we paid a heavy price for it by Everton's swift counter-attacking and better finishing than ours, which has been our problem for many games now."
For Lukaku, it represented a sixth goal in as many matches against West Ham and Allardyce, who felt his side should have been given a first-half penalty for handball, is sick of the sight of the former Chelsea frontman.
"I thought we'd done it finally, at last," added Allardyce. "He hadn't caused us that many problems today. But he was there again to finish us off.
"One good thing is that the lads have learned their lesson since the turn of the year on what happens in the Premier League if you don't focus correctly.
"They'll learn that lesson now when, in the early part of the season when everything was in top gear, they must have thought 'it's not quite as hard as I thought it was this Premier League'.
"But they've seen the realities and the cruelness of the Premier League since the turn of the year and that's a great lesson for them all to learn for next season."
