West Ham boss Slaven Bilic admitted to being worried by his side's form after their winless start to the Premier League season continued at Newcastle.
The Hammers were comfortably beaten 3-0 at St James' Park to leave them without any points after three games.
They have had to play three successive away games as the London Stadium hosted athletics' World Championships.
"Newcastle were better in every aspect of the game. They had simply more power, more determination," said Bilic.
"I am worried. I'm not panicking. It's very early."
"After the game against Southampton, we lost the game, we still had zero points but I was still very, very positive with the way we played, with the way we reacted after we were left with 10 men," added Bilic.
"This is different, this is worrying, but like for every club, it has its ups and downs and nobody will take us out of this situation but ourselves.
"Look, I am the manager, it's my job to be confident and to believe in good and bad times. Even when the times are bad, then you see the importance of the job more than in the good times. I haven't changed in that."
West Ham's next league game is at London Stadium, against Huddersfield, who drew 0-0 at home with Southampton on Saturday to maintain their unbeaten start to the season.
Bilic has spent a reported £42m on players this summer, bringing in goalkeeper Joe Hart, defender Pablo Zabaleta, midfielder Marco Arnautovic and striker Javier Hernandez.
Analysis - 'Bilic looks a broken man'
Former England defender Martin Keown on Match of the Day 2 Extra:
It's gone from bad to worse. I know Bilic was talking about the positives after the Southampton game but losing against Newcastle, another team in big trouble themselves, there are a lot of question marks.
They look like they are all over the place. They have players completely out of form. There isn't a team. They are not gelling together as a group.
You wonder now is it going to be time to change the manager? It's only three or four matches in the season. It seems so early in the season.
But he needs to have a look at himself. Is he up for the job? He didn't look up for the job against Newcastle. He looks like broken man.