The contrast could hardly be greater as for Senegal who started their Africa Cup of Nations title bid with a comfortable 3-0 win over Botswana before Nigeria opened with a nervy win 2-1 victory over Tanzania.
Both teams are among the favourites for the 35th edition of the tournament, but only one lived up to its billing.
Nicolas Jackson scored twice before Senegal substitute Cherif Ndiaye completed the scoring after Botswana goalkeeper Goitseone Phoko kept the scoreline respectable for the Zebras.
The landlocked state lined up with five at the back and were pinned in defence for most of the game.
"We have to keep going like this," said Senegal coach Pape Thiaw, who nevertheless saw room for improvement. "There are no easy opening matches."
Nigeria got a Group C win in the old "imperial city" of Fez, but the performance may cause concern.
"We are satisfied with the three points. That is the most important," a coach Éric Chelle said.
The Super Eagles made the better start and should have scored long before Semi Ajayi finally broke the deadlock in the 36th with a header off Alex Iwobi's cross after a short corner.
Charles M'Mombwa equalised against the run of play early in the second half, and though Ademola Lookman replied almost straight away with a fine strike, the Taifa Stars' goal seemed to drain Nigerian confidence away.
Nigeria star Victor Osimhen, who'd earlier had a would-be goal ruled out for offside, was unhappy when he went off in the 86th.
Ibrahim Hamad missed the last chance for Tanzania, and Nigeria - beaten finalists in the last edition - ultimately had enough experience to hold on.
Elias Achouri scored twice as Tunisia dealt Nigeria a warning with a 3-1 win over Uganda in Group C.
Ellyes Skhiri also scored for the Carthage Eagles, who were buoyed by vocal support, with Denis Omedi getting Uganda's consolation goal in stoppage time.
Nigeria face Tunisia next on Saturday.
An early goal from Théo Bongonda was enough for Congo to beat Benin 1-0 in Group D's first game.
