The Swede netted either side of goals from Henrikh Mkhitaryan and Juan Mata to move the Red Devils to within two points of the top four.
It has been a fine first season in England for the 35-year-old.
Zlatan Ibrahimovic scored as Manchester United thumped Leicester
Manchester United player ratings against Leicester
Sun, February 5, 2017
Express Sport brings you Manchester United's player ratings from their clash with Leicester City
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David De Gea – 7
Zlatan Ibrahimovic celebrates scoring against Leicester
And Ibrahimovic wants even more goals – but is keeping his own goal target to himself.
"I have a target in my head but I will not say it!" Ibrahimovic said.
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"I am not there yet. But I have set a target and that is something I have been doing every year. It is nothing new for me. I keep producing. I do my best and I get a lot of help from my team-mates. I know there were many people who said I wouldn't even score 20 but that is nothing I focus on.
Juan Mata also scored as Leicester were put to the sword
"I have 20 goals and seven assists and the target is in reach like it's been before in other years, except for last year which was a crazy year!
"Everything motivates me – all the targets, all the critics, the atmosphere, coming to the Premier League and bringing more followers to the Premier League."
The former Paris Saint-Germain and Barcelona star will be hoping to add to his goal tally when United go up against Watford on Saturday (3pm).