The early season alarm bells are ringing louder for West Ham after Bournemouth came from behind to win 2-1 at London Stadium on Saturday.
Thrashed 4-0 at Liverpool last weekend, Manuel Pellegrini's side meekly crumbled to a second successive defeat by giving up two soft goals in the space of six second-half minutes.
Callum Wilson cancelled out Marko Arnautovic's first-half penalty with a fine solo effort on the hour and the Cherries' stirring fightback was complete when Steve Cook headed home from a set piece.
Eddie Howe's men, 2-0 winners over Cardiff City seven days ago, have now won four straight Premier League matches for the first time in their history, having signed off from last season with back-to-back victories.
After a subdued start, Javier Hernandez finally tested Asmir Begovic at his near post in the 25th minute, before Lukasz Fabianski came to West Ham's rescue with a superb reactionary save from Wilson's shot on the turn.
David Brooks brilliantly freed Wilson on that occasion and Felipe Anderson soon proved his own eye for a pass, finding the feet of Hernandez who was brought down in the box by Nathan Ake's trailing leg.
Arnautovic stepped up to the spot and the Austria forward made no mistake, firing into the bottom-left corner to put his side ahead in the 33rd minute.
The visitors should have had a spot-kick for themselves soon after the restart, but those frustrations disappeared when Wilson took it upon himself to net the equaliser by breezing beyond five static defenders and coolly converting at the end of a splendid individual effort.
So easily unpicked for that goal, the Hammers' sleepy defence was exposed again six minutes later as Cook wrestled past Angelo Ogbonna to nod home Ryan Fraser's free-kick and complete the comeback, ensuring Pellegrini has significant problems to solve at the start of his tenure.
What does it mean: Pellegrini under the pump
The goodwill West Ham earned from a productive transfer window could soon turn. Their supporters have proven impatient in the past and an edgy atmosphere on Saturday will only worsen if results do not improve in the near future.
Pat on the back: Fabianski in fine fettle
Fabianski can hold his high despite the defeat. The off-season addition from Swansea City looks a shrewd acquisition, having saved superbly from Wilson and Brooks in either half to briefly delay the apparently inevitable.
Boot up the backside: Ogbonna under threat
New signing Issa Diop will surely be thrust into the starting XI next time out. Signed for a reported £22million from Toulouse, the centre-back was forced to watch from the bench as Ogbonna flailed about on both Bournemouth goals, first failing to sense the danger when Wilson strode forward and then being outmuscled by Cook for the second.
What's next?
West Ham make the short trip to Emirates Stadium for a date with Arsenal next Saturday, while Bournemouth return home to meet Everton.
