A header from Robin Van Persie (13), an artistic chip from Angel Di Maria (16) and a deflection from Ander Herrera (57) put United 3:1 ahead, against a header from Leo Ulloa (17).
But United’s shaky defence conceded a penalty to David Nugent (62) then an equaliser to Argentinian Esteban Cambiasso (64), making his first start for Leicester after his fee-free move from Internazionale. Jamie Vardy put Leicester ahead (79) then forced another penalty. Ulloa converted this one (83).
Centre-forward Vardy won the man of the match award, less than three years after being fished out of non-league football.
United manager Louis Van Gaal said: “The spectators have seen a fantastic spectacle again. We scored fantastic goals and should have won the game. We didn’t do that because we did not keep possession.
“We had too many players who wanted to chase the extra goal. You cannot afford that against a team like Leicester who came back very well. We made big errors as a team and as individuals.”
** West Bromwich moved off the bottom of the table with their first win of the season by 1:0 at Tottenham on a late header by Scotland midfielder James Morrison. This was Albion’s first win at White Hart Lane in 30 years.