Morocco, whose chances of winning the African Nations Cup are rated as slim at best by their coach, beat Nigeria 1-0 with a superbly-taken winner from substitute Youssef Hadji.
Hadji received a long pass by Abdelkrim Kaissi with his back to goal, turned and fired the ball past Vincent Enyeama in the 77th minute to stun the Super Eagles.
Nigeria, with a vastly more experienced team including several players based in the Premiership, barely mustered a chance in their spluttering debut to the competition.
Morocco, who fell at the first hurdle in the last two Nations Cup finals, are rebuilding their team almost from scratch under former international Bedou Ezaki.
Their 1986 World Cup goalkeeper said on Monday his countrymen were dreaming if they thought their team had a serious chance of winning the title. His team dominated the first half, however, winning almost every 50-50 ball, forcing nearly a dozen corners and creating the best chances.
At the other end, their defence, marshalled by Noureddine Naybet in his 98th international, kept the Nigerian attack under wraps. Nigeria's big-name players were strangely subdued.
Playmaker Jay-Jay Okocha produced a few clever flicks but his long balls forward never found the target, Nwankwo Kanu barely touched the ball and at the back Isaac Okoronkwo kept getting himself into a tangle. Arsenal's Kanu, playing an unfamiliar midfield role, was replaced after 72 minutes.
Morocco should have gone ahead in the 19th minute when Jawad Zairi, their most dangerous player, dispossessed Isaac Okoronkwo on the right and produced a perfectly flighted cross into the path of Marouane Chammakh at the far post but the Bordeaux striker headed over.
Zairi was replaced by Hadji in the 59th minute and the substitute continued to torment the Nigerian defence until he was rewarded with the winner. Chammakh came agonisingly close to a second when his shot hit the inside of the post two minutes from time.