Tottenham captain Son Heung-Min said the players needed to "look in the mirror" after an "unacceptable" 3-0 loss at Fulham cast doubt on their Premier League top four credentials on Saturday.
Victory would have put them ahead of Aston Villa into the guaranteed Champions League berths but Spurs produced a limp display and failed to score in a league match for the first time this season.
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"It is very disappointing and very frustrating. Everybody has to look in the mirror and say 'it is my fault'," Son said.
"It was not good enough. We didn't put in the effort we have put in this season. The performance, the attitude was not good enough. Everyone needs a big wake-up call."
The performance was all the more surprising given Tottenham's clinical 4-0 win at Villa last weekend.
"In the Premier League if you are not ready you get punished," the South Korea forward added. "Aston Villa are an amazing team, but so are Fulham. If you are not giving 100% you get punished. You don't get three points for free.
"This is two steps backwards. We now need to step forward. It is unacceptable, including me it was unacceptable.
"We are representing Premier League teams, we are representing Tottenham. This was not close to what we have been doing this season. It is very sad to watch this. The fans don't deserve this. Losing this was very tough."
Spurs boss Ange Postecoglou said he was particularly disappointed with his team's second half performance.
"To be fair to the players, it's the first time this year where I've felt, especially in the second half, that we just didn't... We're in the position we are because every week we've been really, really competitive in every aspect of the game and even in our losses I've felt like we've hit certain markers in terms of our endeavour and competitiveness and I thought that it was missing today and that was disappointing," Postecoglou said.