The centre-forward struck all four goals in the 4-1 win at the Foxes.
Advertisement
Advertisement
Obi scored twice in each half as the win sent United top of the U21 Premier League table.
The centre-forward still qualifies for the U18s and is part of United's FA Youth Cup run this season.
Obi tasted first team football last season with United, though has been held back this term to accelerate his development.