Wilfred Ndidi scored his first goal this season for Leicester City to shoot to the top of Group C of the UEFA Europa League, while Ike Ugbo rescued a crucial point on the road for Genk in the same competition.
Ndidi rose highest to deliver a free header from a corner in the 33rd minute for Leicester City to lead 3-1.
He made up for the penalty he caused that led to Legia goal.
Ademola Lookman delivered an assist, while Kelechi Iheanacho was a late sub.
Leicester City now lead the standings on eight points from five matches after they started bottom.
However, they face a daunting final group game at Napoli on December 9.
Napoli are third on the table with seven points, same as second-placed Spartak Moscow, while Legia Warsaw bottom on six points.
In Group H, Genk are third on five points from as many matches after they forced a 1-1 draw at Dinamo Zagreb thanks to an equalizer by Ike Ugbo in the 45th minute.
A win next month in their final group game at home against bottom side Austrian club Rapied Wien could still keep them alive in this competition.
