Mama Balde scored the only goal as Guinea-Bissau defeated Nigeria 1-0 in an Africa Cup of Nations qualifier on Friday.
The match was played at the Abuja National Stadium in the FCT.
The loss continues a three-match winless run for the Super Eagles.
In the early stage of the match at the MKO Abiola stadium, Samuel Chukwueze’s shot was blocked by a band of defenders after Alex Iwobi stroked a grounder to him at the edge of the box.
A few minutes later, Osimhen had the opportunity to score but his toe-poked effort was thwarted by Jonas Mendes, the Guinea-Bissau goalkeeper, after a defence-splitting pass from Kelechi Iheanacho.
The Djurtus grew into the match from there on, occasionally exploiting space created by the defensive pairing of Kevin Akpogoma and Cavin Bassey.
The away team’s effort was rewarded in the 26th minute after a long ball from their half travelled through a fallow Nigerian central defence.
Mama Samba Balde chased the floated cross-field pass with Bassey and Akpoguma only catching up after the Bissau-Guinean slotted the ball into the net through the legs of Francis Uzoho.
The goal stunned the handful of Nigerian supporters in the stadium.
Guinea-Bissau almost doubled the lead a few minutes later but Dalcio only scooped the ball into the side netting after eliminating Iwobi off a counterattack.
Peseiro sent on Paul Onoachu and Moses Simon for Kelechi Iheanacho and Ademola Lookman at the beginning of the second half and the changes rejigged the Eagles’ attack.
Moses dragged a shot wide after a cutback from Chukwueze and Ndidi’s weak effort of a through pass from Osimhen was halted by a recovering defender.
The Eagles failed to beat the Djurtus who held on for a vital victory to go top of the group with seven points.
The result means Guinea-Bissau are defeating Nigeria for the first time in history.