Bruno Fernandes, celebrating his 250th appearance for United, was instrumental in the 3-0 victory, scoring one goal and directly contributing to two others.
Fernandes opened the scoring before Kristiansen’s unfortunate own goal doubled United’s lead.
Later, substitute Alejandro Garnacho delivered a sensational strike, sealing the Red Devils’ triumph at Old Trafford.
Midfielder Manuel Ugarte also impressed, turning in what many fans called his best performance in a United shirt.
Leicester managed a reasonable share of possession and could have posed more of a threat.
However, their lack of sharpness in the final third left them unable to capitalise on promising moves.
Meanwhile, in one of the day’s biggest surprises, Ipswich Town ended a 22-year wait for a Premier League win by defeating Tottenham Hotspur 2-1 in North London.
Sammie Szmodics opened the scoring in the 31st minute with a spectacular overhead kick, and Liam Delap doubled the lead just before half-time, narrowly avoiding credit going to Spurs defender Radu Dragusin for an own goal.
Although Rodrigo Bentancur pulled one back with a header from a corner, Ipswich held on for a famous win.
This result leaves Manchester United just a point behind Tottenham in the league standings and marks a historic victory for Ipswich, who had not won a top-flight match since April 2002.
For the Tractor Boys, it’s a memorable return to winning ways, as they hope this marks a turning point in their long-awaited Premier League comeback.