Jose Mourinho's position as Tottenham manager is under further scrutiny after a damaging 2-1 defeat at West Ham on Sunday as Leicester moved into second by beating Aston Villa by the same score.
Spurs have now lost five of their last six league games to fall nine points off the pace in the battle for a top-four finish. They are now ninth in the table.
"The results are the consequences of multiple situations in football. Mine and my coaching staff methods are second to nobody in the world," said a defiant Mourinho.
"Our potential is higher than where we are so there is frustration."
Mourinho's men were undone by a slow start to each half at the London Stadium.
Michail Antonio opened the scoring after just five minutes before the rejuvenated Jesse Lingard smashed home the third goal of his loan spell from Manchester United two minutes into the second half.
Tottenham rallied after Lucas Moura's powerful header pulled a goal back.
Gareth Bale impressed in his appearance as a second-half substitute as he thundered a long-range strike against the bar.
Son Heung-min also struck the post in the dying stages after the ball rebounded off the South Korean, but West Ham held on to move into fourth.
"We are enjoying it but are also not going to be daft," said Hammers boss David Moyes, who enjoyed his first win over Mourinho in 16 attempts. "We will keep calm and hopefully keep pushing the teams at the top."
Villa suffer without Grealish
Leicester are determined not to make the same mistakes of last season when they let a huge lead over Manchester United and Chelsea slip away and missed out on Champions League football on the final day of the campaign.
The Foxes now enjoy a six-point cushion over Chelsea in fifth thanks to a flying start against a Villa side who badly missed injured captain Jack Grealish.
James Maddison could be the beneficiary if Grealish's leg injury forces him to miss England's World Cup qualifiers next month and he continued his fine scoring form with a low drive that clipped the inside of the post.
Leicester were 2-0 up inside 23 minutes as Harvey Barnes then pounced after Emiliano Martinez saved from Jamie Vardy.
Villa were handed a lifeline three minutes into the second half when Bertrand Traore swept home Matt Targett's cross, but lacked the creative spark for which they rely on Grealish to find an equaliser.
Victory for Brendan Rodgers's men cuts Manchester City's lead at the top to seven points ahead of their visit to Arsenal later on Sunday.
Manchester United can also reclaim second on goal difference when they host Newcastle.