Tottenham manager Mauricio Pochettino says his players have not got the right "mentality" at the moment as they suffered their third loss at home this season with a 2-1 defeat by Newcastle.
Emmanuel Adebayor had given Spurs the lead in the 18th minute, before two goals early in the second half saw Newcastle snatch victory.
"We need to improve a lot [to get in top four]. It's not tactical or physical it's our mentality," he said.
"It's a big hit for us."
He added: "We need to be more strong and to have more focus. Today in the second half, straight from the kick-off we conceded a goal. It's crazy."
That goal came from half-time substitute Sammy Ameobi, who eased past marker Eric Dier to score within 10 seconds of the restart. Spanish striker Ayoze Perez scored a second with a header in the 58th minute.
"Seven or six seconds before [the first goal], all was happiness and there was good energy in the stadium. Our supporters were happy and believed that we would get a good result," continued Pochettino.
"But in this moment, I think it was difficult to manage in our head. Our heads had gone and we started to take rash decisions on the pitch.
"It was difficult because 12 or 14 minutes later, we conceded another goal. At 2-1, it was difficult."
The north London club have now only won once in the Premier League in seven attempts. Sunday's defeat leaves them 11th with 11 points from nine games.
Asked about the effect of Spurs' European commitments, the Argentine said: "It's not easy to compete in the Europa League and Premier League.
"Today it was about a lack on concentration at the start of the second half. We conceded and then the head is gone. It's hard to get the concentration."