Arsenal and Tottenham grabbed late winning goals against title rivals on Sunday to move two points off the lead as the race to win the English Premier League tightened up.
Leicester started the weekend with an unlikely five-point lead but conceded in the fifth minute of stoppage time to lose 2-1 at Arsenal, with Danny Welbeck scoring the winner in his first match back after 10 months out injured.
"This strengthens our belief that we are in the fight," Arsenal manager ArseneWenger said. "It would have been massive for us to lose."
It was only Leicester's third loss of the season - and two of them have been inflicted by Arsenal.
Christian Eriksen didn't leave it quite so late for Spurs against Manchester City, slotting home in the 83rd minute to also seal a 2-1 win at Etihad Stadium. It will be regarded as a landmark win for a young Tottenham team that is going for the club's first league title since 1961.
"It is true our supporters can dream," Spurs manager Mauricio Pochettino said.
Second-place Tottenham leads Arsenal on goal difference, while City's second straight home loss kept the team six points behind Leicester, with its squad beginning to look stretched as it goes for trophies on four fronts.
In the other match, last-place Aston Villa slipped to its heaviest home defeat in 81 years, losing 6-0 to Liverpool. The visitors had six different scorers, including Daniel Sturridge in the injury-prone striker's first league start for more than four months.
Relegation candidates all of last season, Leicester is dealing with a different kind of pressure this time round but a failure to handle rising expectations wasn't the reason behind the defeat at Emirates Stadium.
The biggest factor was probably the sending-off of right back Danny Simpson after two yellow cards in the opening nine minutes of the second half. Leicester was then leading 1-0, thanks to Jamie Vardy's penalty on the stroke of halftime - his league-high 19th goal of the season.
Substitutes came good for Arsenal. Theo Walcott equalized with 20 minutes to go with Arsenal's first shot on target and fellow sub Welbeck, who came on in the 83rd minute, headed in Mesut Ozil's free kick.
"Everybody is extremely happy for him, because he has been out for 10 months - that is an eternity for a player," Wenger said.
Spurs capped a successful day for the north London clubs by completing a league double over City, another sign that they are ready to finally challenge for the championship under Pochettino after years of underachievement.
Harry Kane put Tottenham in front in the 53rd from a penalty that was controversially awarded for a handball against Raheem Sterling, who turned his back to a cross from Danny Rose. The ball appeared to strike a combination of his elbow and back, with his arm with his arm not outstretched.
Substitute Kelechi Iheanacho equalized in the 74th, only for Eriksen to race onto Erik Lamela's through-ball and slip a low finish past goalkeeper Joe Hart.
With 12 games left, City is now dependent on three teams above it dropping points.
"The first problem is our team," City manager Manuel Pellegrini said. "We need to improve in a lot of things."
It is the first time since 1985 that Tottenham has been second at this stage of the season.
After Sturridge and James Milner secured a 2-0 lead at halftime, Liverpool scored four goals in 13 second-half minutes - through Emre Can, Divock Origi, Nathaniel Clyne and Kolo Toure - to seal its biggest win under Juergen Klopp.
Liverpool climbed to eighth place, three points behind fifth-place Manchester United, while Villa is eight points from safety.