Manchester United fell further behind Manchester City at the top of the Premier League when defender Harry Maguire scored in the final minute of added time to earn Leicester City a 2-2 draw on Saturday.
They were left 13 points behind their irrepressible neighbors at the halfway stage of the campaign.
Jamie Vardy and Riyad Mahrez combined for Vardy's 50th Premier League goal in the 27th minute, the Algerian holding up Wilfred Ndidi's pass for Vardy to score.
Juan Mata equalized before halftime after Jesse Lingard touched Anthony Martial's cross to him, then scored with a direct free kick.
Leicester looked doomed when they had substitute Daniel Amartey sent off only 17 minutes after he came on, for two yellow cards in quick succession.
But in the fourth minute of added time England defender Maguire slid in Marc Albrighton's cross.
United manager Jose Mourinho was left cursing "childish" errors at both ends of the pitch.
"We didn't win because we missed incredible chances, joke chances," he told Sky Sports.
"We made a big defensive accumulation of mistakes in an easy match to win. I told to the players at halftime when it was 1-1 that it was an easy match to win.
"Half an hour after our second it is a game to finish four, five, six-one.
"We were punished by our mistakes. Childish loss of possession, so easy. Childish in their box and childish in our box."
The worst of the wasted chances he referred to were set up in the second half by Romelu Lukaku but frittered away by his team mates.
The Belgian put through first Martial, who fired wildly over the bar, and then Lingard, also clean through, who could only hit a post.
That led to an anxious last few minutes even against 10 men.
Defender Chris Smalling was injured and in no position to clear when Maguire got on the end of Albrighton's cross to the far post.
For the first goal Phil Jones had been lured out of position and could not catch Vardy as the England striker raced onto Mahrez's pass.
For Leicester it was nevertheless a spirited recovery to continue their good form under new manager Claude Puel.
"The manager has come in and results have picked up," said Maguire.
"Last-minute goal to equalize, that is massive for us.
"It feels like a victory but it is only a point against a good side."