Ange Postecoglou said Tottenham lacked “belief and conviction” but promised to find a fix as their Champions League hopes suffered a blow with defeat at Chelsea.
Spurs were beaten 2-0 at Stamford Bridge and are now seven points behind fourth-placed Aston Villa, albeit with a game in hand.
Tottenham have games against Liverpool and title-chasing Manchester City among their remaining fixtures and have now lost three in a row in the Premier League.
“They’ve lost a little bit of belief and conviction in their football and that’s for me to fix,” Postecoglou said of his side.
Tottenham made an excellent start to the season under Postecoglou and their free-flowing football was praised as the former Celtic manager looked to bring Champions League football back to the club.
However, Spurs have won just two of their latest seven games and it leaves them needing to sharply find a return to winning ways while hoping that Villa slump.
Headed goals from Trevoh Chalobah and Nicolas Jackson gave Chelsea a well-earned league success over their London rivals.
“It wasn’t a great night for us. We didn’t play at the levels we needed to and didn’t deserve something from it,” Postecoglou said.
“We lacked belief and conviction in our game.
“I don’t know if it is low confidence, but we are not playing with the mindset we need to play the football we want to, and that is something I have to look at.
“It is on me to fix it. That is what we will be doing.”
Asked how he would “fix” Tottenham’s failing form, Postecoglou said: “Just hard work, mate, there’s no major formula. We will work hard and make sure we get it right.”
As Spurs suffered, it was a positive night for Chelsea boss Mauricio Pochettino, taking charge of his 400th game in English football.
The 52-year-old Argentine, who managed Tottenham from 2014 to 2019 and took them to a Champions League final, has led Chelsea to a double over Spurs after Thursday’s victory followed a 4-1 win in November.
This latest win means big-spending Chelsea now sit in eighth place, just two points behind Newcastle United in seventh and a possible European spot – with sixth-placed Manchester United just one point better off than the Magpies.
Pochettino was not convinced it was “the best game” but said it left him feeling “the most happy” he could be.
“In the way that we play and the way that we compete, that is what we wanted from the beginning of the season,” Pochettino said.
“Today we were so competitive. In this way we can grow and do better and improve in all the areas.”