West Ham boss Manuel Pellegrini admitted he is worried by "big mistakes" after a 3-0 defeat at Burnley condemned his side to a sixth winless league game in a row.
The Hammers have picked up just one point in that run since an impressive 2-0 victory over Manchester United had taken them to the dizzy heights of fourth place.
Now they are looking over their shoulders as they are overtaken by their hosts to stand in 16th place just five points off the relegation places.
They have now shipped 13 goals in those six games and it was defensive frailties that let them down again at Turf Moor.
All three goals were preventable and, but for some heroics late on by keeper Roberto who had early scored an embarrassing own goal when punching into his own net from a corner, the defeat could have been more damaging.
"Of course it is a concern how the performances have dipped," said Pellegrini. "It is a very difficult moment, but we have to perform as a team.
"In this moment we have a lot of poor performances from a lot of players and now we are trying to recover, not only the results but the trust, too.
Asked if today's performance was acceptable, the Chilean added: "I don't know, but there were big mistakes for the goals.
"The first goal was a set-piece, it was a corner which was not a corner so that was a mistake from the referee, but we must defend it anyway. Then there were two big mistakes.
"It is more than confidence, we are conceding too many goals. Three against Newcastle, three set-pieces. If you concede so many difficult goals, it's very difficult to win."
Such was their fragile confidence that conceding an early goal proved disastrous for the Hammers.
James Tarkowski rose highest at the back post to nod down a Dwight McNeil corner and Ashley Barnes, who signed a new deal during the week, poked home from close range.
The home side were denied a second when a Chris Wood header was ruled out by VAR for offside, but the New Zealander was soon on the scoresheet when McNeil pounced on sloppy defending from Fabian Balbuena and his low cross was volleyed home by the unmarked Wood.
Fortunes continued to dive for the Hammers after the restart and any chance of a comeback went out the window when Roberto flapped at an Ashley Westwood inswinging corner and he could only divert the ball into his own net.
Clarets boss Sean Dyche was delighted with the way his players bounced back from their worst display of the season last season when they went down by the same 3-0 scoreline to newly-promoted Sheffield United.
"Our alter ego - last week we weren't even close to a performance," said Dyche. "We were way off the mark. Today, it came flooding back in. The edge we played with, the organisation, the shape and belief."
By Russell Stoddart
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