West Brom halted Leicester’s title charge with a hard-earned 2-2 draw at the King Power Stadium on Tuesday.
The Foxes are three points clear of second-placed Tottenham, who go to West Ham on Wednesday, after being frustrated by the battling Baggies.
Goals from midfield duo Danny Drinkwater and Andy King cancelled out Salomon Rondon’s early opener before Craig Gardner’s classy free-kick earned a point for Albion.
Jamie Vardy and Shinji Okazaki hit the bar for the hosts, who were the better side, and Wes Morgan blew a glorious chance to win it late on.
Claudio Ranieri’s side will now face an anxious wait when Spurs go to Upton Park, where a win for their title rivals will be enough to send them top on goal difference.
The Foxes’ pre-match points tally of 56 was already their highest ever in the top flight but cracks showed despite their late 1-0 weekend win over Norwich.
The Canaries stifled Leicester for much of the game and Albion set about doing the same early on before taking a surprise early lead.
Darren Fletcher spotted the run of Rondon after 11 minutes and the striker out-muscled Robert Huth in a heavyweight clash on the edge of the area before poking his shot through the legs of the onrushing Kasper Schmeichel.
In doing so, Albion became just the third visiting side in the league this season – after Tottenham and Aston Villa – to score first at the King Power Stadium.
It sparked Leicester into action and Okazaki volleyed over from six yards.
Vardy should have levelled on 27 minutes when, unmarked, he headed straight at Ben Foster from Riyad Mahrez’s cross.
The Foxes, though, were building momentum and grabbed the equaliser three minutes later.
A corner routine was worked back to Drinkwater 25 yards out and the midfielder’s drive clipped Jonas Olsson to loop in over Foster.
The goal, Leicester’s 50th in the league this season, was fortuitous but the hosts capitalised and maintained their drive, only for Vardy’s header to smack the bar after 36 minutes.
Since levelling the hosts had been the better side – although nowhere near their fluid selves- but did find a second in first-half stoppage time.
There had been little flowing football from the hosts but the Foxes conjured a sweeping move when Marc Albrighton’s crossfield pass found Mahrez and he teed up King to steer in from 15 yards.
The midfielder, in the team because of N’Golo Kante’s hamstring injury, had not scored in the league for 11 months.
But Albion hit back just four minutes after the break when, following Mahrez’s handball, Gardner curled a brilliant free-kick past the motionless Schmeichel from 25 yards.
It allowed the game to take a similar pattern to the first half with Albion scoring early and Leicester pressing.
And just like the first period the Foxes hit the bar when Okazaki shuddered the woodwork with a 57th-minute header.
It was a glaring miss from the striker but the chances kept flowing as Jeff Schlupp’s drive deflected at Foster minutes later.
Rondon then hacked over from close range as the game opened up before Foster denied Vardy – after he outpaced Gareth McAuley – with 20 minutes left.
Both sides pushed for the next goal, with Gardner shooting over and Huth heading wide, but the Foxes looked more likely to grab a priceless winner.
And, with four minutes left, Morgan almost found it when Olsson slipped in the area but the Foxes’ skipper was denied by Foster from 10 yards.
Mahrez then volleyed wildly over and Leonardo Ulloa could not force the ball in during stoppage time as Leicester were forced to settle for a point.