Mauricio Pochettino insists he needs time to implement his methods at Tottenham but admits results must improve after Spurs slipped to a 2-1 defeat at home to Stoke on Sunday.
Stoke were two ahead before the break thanks to strikes from Bojan Krkic and Jonathan Walters and the Potters held off a late Tottenham rally after Nacer Chadli had given the hosts hope late on.
Spurs have now lost four out of their last five home games in the league and the latest defeat sees Pochettino's men drop to 12th in the Barclays Premier League table.
"It's clear from the results that we need to improve, we need to improve a lot," Pochettino said.
"It's another defeat and we need to improve, this is clear to see.
"In football you always need time to implement different methods but we need to improve quickly because you never have a long time in football.
"You need to get results and we need to find a solution quickly. My challenge in the next few weeks is to change the mentality and to find that solution."
The atmosphere at White Hart Lane was nervy from the off and the home fans regularly vented their frustration after Stoke took an early lead.
Pochettino admits his players went into their shell after Bojan's opener and says they needed to show more courage to turn the contest around.
"When we conceded the first goal, we felt the pressure," Pochettino said.
"When you play the way we want to play, you need to feel confident on the pitch because it's important to create the space, to be patient with the ball.
"It's true that when we conceded the goal we started to take rash decisions and felt uncomfortable in possession."
Pochettino continued: "We have to find a solution and change the mentality.
"We conceded a goal after six minutes and then the team needed a lot of time to recover the performance. This is what we need to change."
Pochettino substituted Christian Eriksen at half-time for the second consecutive league game and also took Andros Townsend off at the break.
The Argentine boss insists the pair were replaced for "tactical reasons" and that all the players shared his disappointment in the dressing room.
"They know my feelings and I know their feelings," Pochettino added.
"We have been here for months and we know the players and the players know me.
"We feel the same. We are very disappointed and frustrated and not happy because our performance was not good enough."