Gernot Rohr’s men were humiliated by the island nation, who are making their debut appearance at the tournament.
A goal in each half of the encounter from Lalaina Nomenjanahary and Carolus Andriamahitsinoro moved Nigeria to second spot, while Madagascar became the seventh nation to go unbeaten in their first three AFCON games since Cape Verde in 2013.
“I think this is a wake-up call for us, today, we played very poorly, we were relaxed and our mentality was not very good.
“Probably it is because we were already qualified but this game has shown us that there is no easy team in this competition.
“We have to go back, regroup and ensure we do well for the next game which is a match with no room for mistakes,” Ighalo told reporters.
The Shanghai Shehua frontman has scored just once in his three appearances so far.
