But Arsenal could not hold on to the lead given to them by Leandro Trossard’s first goal for the club in his fifth appearance since his January move from Brighton.
Ivan Toney scored Brentford’s equaliser to leave Arsenal without a win in their last three games in all competitions following defeats at Manchester City in the FA Cup and Everton in the league.
The Gunners still control their destiny as they chase a first Premier League title since 2004, but champions City can move to within three points if they beat Aston Villa on Sunday.
Arsenal host City on Wednesday in a clash that will go a long way to deciding the title race.
Belgium forward Trossard came off the bench to make the breakthrough for Arsenal in the 66th minute.
Bukayo Saka floated his cross to the far post and Trossard was on hand to net with a clinical finish, his first goal for either Arsenal or Brighton since October.
But Brentford drew level eight minutes later when Toney headed into an empty net after the Arsenal defence had failed to deal with a high ball.
Tottenham boss Antonio Conte was back at the helm after missing last weekend’s 1-0 win against Manchester City following gallbladder surgery, but his fifth-placed side were humiliated at the King Power Stadium.
Rodrigo Bentancur put Tottenham ahead in the 14th minute, meeting Ben Davies’s flick with a close-range finish that survived a VAR check for offside.
But Nampalys Mendy levelled in the 23rd minute when he bagged his first goal for the club with a rocket from the edge of the area.
Two minutes later, James Maddison latched onto Kelechi Iheanacho’s pass and produced a composed low finish.
Iheanacho scored Leicester’s third in first half stoppage-time with a curler into the bottom corner and Harvey Barnes completed the rout in the 81st minute.
Graham Potter admitted Chelsea are still “a work in progress” after their winless Premier League run extended to three games as Joao Felix’s first goal for the Blues was cancelled out by Emerson in a 1-1 draw at West Ham.
Potter’s expensively assembled side once again failed to live up to their price tags as the pressure mounted on the Blues boss.
Portugal forward Felix put Chelsea ahead in his second appearance for the club, only for Italy defender Emerson to haunt his former team with an equaliser before half-time.
Ninth-placed Chelsea have won just one of their past eight games in all competitions and are nine points adrift of the Premier League’s top four.
“The second half was more of a reflection of where we are in terms of integrating new players and getting players up to speed in the Premier League,” Potter said.
“They are a good group and we are excited with the team and the potential but it is still a work in progress.”
Ten-man Wolves boosted their bid to avoid relegation with a 2-1 win at bottom of the table Southampton.
Carlos Alcaraz netted his first goal for Southampton midway through the first half.
Wolves had former Southampton midfielder Mario Lemina sent off moments later for two bookings in quick succession.
But Jan Bednarek’s 72nd-minute own goal turned the tide before Joao Gomes won it for 15th-placed Wolves at the death.
Crystal Palace’s James Tomkins rescued a 1-1 draw against Brighton with a 69th-minute equaliser after Solly March put Albion ahead six minutes earlier at Selhurst Park.
Goals from Willian and Manor Solomon gave Fulham a 2-0 win against Nottingham Forest at Craven Cottage.