Mauricio Pochettino believes it could take five to 10 years for his Tottenham side to win a Premier League title after the weekend loss to Burnley.
Immediately after the 2-1 defeat, the Argentine conceded his side's challenge was all but over as Spurs missed the opportunity to move to within two points of Manchester City and Liverpool.
But he has now gone one set further by suggesting his side lack a long-term winning mentality to succeed.
"If you want to be a real contender, playing well or not, it's (the game against Burnley) a must-win," Pochettino said.
"You need to show you are fighting for big things and I am frustrated because we didn't show the same energy as Burnley, the same attitude as Burnley, the same ambition as Burnley.
"We have to look at ourselves and maybe assess ourselves in different ways - we are not looking for excuses.
"It is holding us back and it might take five years' work, 10 years' work to change that."
Tottenham make the short trip to Stamford Bridge on Wednesday evening (kick-off 8pm) to face losing Carabao Cup finalists Chelsea.
And Pochettino is in no doubt his side will be in the right frame of mind for that encounter - which is part of Tottenham's overall problem.
"To go away and play the likes of Chelsea, Arsenal - that is easy," Pochettino added. "You don't need a manager to motivate you for those games, that is normal.
"But if we don't have the will to show that (against Burnley), then you don't deserve anything.
"What we showed on Saturday was that we are a good team, have good quality but not enough to win a Premier League title - that is the reality.
"If you are not able to beat Burnley it is impossible to think you will win the title - if you do it's because others have lost the opportunity themselves.
"The reality is that it will be tough to win the Premier League because of us, not because Liverpool or Manchester City are any better."