Everton boss Marco Silva said his side did not play with enough quality to win their game against West Ham.
A first half brace from Andriy Yarmolenko put the visitors in control, before Everton's Gylfi Sigurdsson pulled a goal back on the stroke of half-time.
Speaking to BBC Sport after the game, Silva said: "We didn't play with enough quality to win the match.
"We started well with good pace and intensity, but we made mistakes, and at that moment we didn't react well.
"But even after the 1-0 we had a clear chance to score. We didn't perform well, but they had three chances and they scored three goals. We had four or five chances and we scored one goal.
"It's a tough result for us. A club like us to lose 3-1 at home is always tough. We have to react - there's nothing more to it. We have to react to the mistakes we made."
Everton midfielder Morgan Schneiderlin was surprisingly substituted in the first half with just two minutes remaining until half-time, with Brazilian Bernard replacing him.
The Frenchman had surprised fans by making himself available for selection, having lost his father earlier in the week.
However, Silva said the move to replace the midfielder was entirely a tactical decision. He explained: "It was a tactical change, nothing more."
Everton's next fixture is a trip to Arsenal on Sunday, before a Goodison Park clash with Fulham.