Nuno Espirito Santo claimed "everything bad happens" to West Ham, as he rued his side's Premier League defeat to Fulham.
West Ham suffered their seventh defeat in nine matches, going down 1-0 in the London derby.
Raul Jimenez's late header condemned the Hammers to a record-equalling 11th home league loss in a calendar year, which last occurred in 1967.
It also extended their winless streak to seven matches, leaving them 18th and five points from safety.
West Ham had produced an improved second-half performance, but their failure to convert chances – with Jarrod Bowen steering their best one wide from inside the six-yard box – proved crucial.
"It [the goal] comes after some chances we had in the second half. We have been punished by a mistake, and we lose the game," Nuno said.
"Everybody cares, it's not about that, but about the situation we are in. Everything bad happens to us. You can argue about the justice of the result, but the reality is we lost after what I think was an equal first half.
"Second half, we had the momentum, created situations we should have scored from. In the end, we were punished. When you don't score, you are never totally comfortable.
"We have to react. The good part is we play another game [against Brighton and Hove Albion on Tuesday]. It's another chance to give back to our fans."
As for Fulham, they climbed into the top half of the table following a third straight league win.
Jimenez was the hero courtesy of his seventh Premier League goal against West Ham, his most against a single opponent in the division.
"It's special for us to be winning three games in a row," the Mexican forward said. "We are happy to finish the year with a win, and we want to start next year with the same.
"We are playing well, having control of the games. We know we are going to have our chances to score. It was late, but in the end it's 1-0 and we go home with three points.
"It's always important to keep this good form. We have been together. We wanted to start the season like this, but different things [happened]. Now we are in good form, we don't want to lose it.
"We want to go as high [in the table] as possible. It's tough, the league is really competitive. We can be there but must continue working. It's a tough period of games and we must win as many of them [as possible]."
Whuligan
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Comes January transfer Window, Nuno need to do something for every department