Rafa Benitez says Newcastle United were undone by "two moments of quality" against Arsenal.
Benitez's side were beaten 2-1 at St James's Park this afternoon, and the club, without a win so far this season, remains 18th in the Premier League.
Second-half goals from Granit Xhaka and Mesut Ozil claimed all three points for Arsenal.
Substitute Ciaran Clark netted a late consolation goal for Newcastle.
"Two moments of quality changed the game," said United manager Benitez. "We did enough in the first half to score and show we can compete against this kind of team, but it was hard once we conceded the two goals and our goal came too late.
"It's always about a short blanket, because when we attacked to try to get back into the game, we left ourselves open to the counter-attack."
United have played four of last season's top six, and Benitez believes the club's league positions reflects the opposition they have faced so far this season.
Asked if he was worried, Benitez said: "No. It's a difficult time because you have to win games.
"I'm not concerned, because I know my team and I know that we can do well.
"We're run all the top sides we've played close so far this season. Arsenal had two shots on target and they scored two goals.
"The fans they see from the beginning they can see the picture. To lose by a narrow margin against the top sides is something we could expect, but having said that, we're not happy about it."