Mauricio Pochettino fears Tottenham have blown their chance of winning the Premier League because they lack the ruthless streak required to succeed under intense pressure.

Pochettino's side crashed to a shock 1-0 defeat at West Ham on Friday that left their title bid in tatters and put Chelsea within touching distance of being crowned champions.

Rocked by Manuel Lanzini's second half strike, second-placed Tottenham remain four points behind the leaders and the title race could be over by the time they return to action against Manchester United on May 14.

Chelsea need six points from four games to guarantee top spot and they would reach that target with wins against Middlesbrough on Monday and West Bromwich Albion on Friday.

It is a painful prospect for a Tottenham side that had won their previous nine league games to spark dreams of a first title since 1961.

But Pochettino knows they can have few complaints after a strangely lethargic display lacking both poise and passion.

Tottenham's tame surrender recalled their collapse at the end of last season when they squandered opportunities to catch eventual champions Leicester.

And Pochettino conceded his players came up short when they most needed to show they could cope under duress.

"We have to analyse why it was difficult to get the points here," Pochettino said.

"To win a trophy you have to show in a key moment you can win. Today was a key moment.

"There are games you must win, it's not about playing good or bad, or running more or less. We were missing a little bit.

"If you want to be champions you must win. How? I don't know. But you have to win."

After a stylish victory over north London rivals Arsenal on Sunday, Tottenham suddenly lost their swagger at the worst possible time.

Pochettino refused to condemn his players' lack of fight, but his deflated tone when he faced the media in his post-match press conference told a different story.

"It wasn't our best day. The performance was just ok," he said.

"We conceded the sort of goal you do not concede when you are a team fighting for big things.

"I don't change my vision of my players. I'm very proud. It's so difficult sometimes to keep your level."