Debutants Madagascar picked up their first ever point at an Africa Cup of Nations after playing out a 2-2 draw against Guinea in their Group B opener.
Guinea, without the powerhouse midfielder Naby Keita with the Liverpool player only fit enough for a place on the bench, took a first-half lead through Sory Kaba before Anicet Andrianantenaina levelled matters four minutes after half time.
On 55 minutes the Indian Ocean islanders took took the lead when Charles Andriamahitsinoro produced a nerveless finish after latching onto a hopeful punt forward.
A Francois Kamano penalty salvaged a point for Guinea following a foul on captain Ibrahima Traore on 66 minutes.
Madagascar are one of three teams appearing at the expanded 24-nation event for the first time.
Burundi, one of those three teams, were 13 minutes away from also securing their first point at Afcon before Odion Ighalo came off the bench to fire the only goal of the game in Alexandria on Saturday.
Ighalo, set free by Ola Aina's clever flicked pass, side-footed the ball past Burundi goalkeeper Jonathan Nahimana in the 77th minute, four minutes after coming on in the opening Group B match.
It was tough on Burundi who refused to be overawed and enjoyed slightly the better of the first half, with Frederic Nsabiyumva heading against the crossbar from a set-piece.
"We couldn't have produced a better performances because Burundi were very organised," said Nigeria manager Gernot Rohr.
"We knew Burundi were unbeaten in the qualifiers, and we knew the first matches would be difficult. These teams don't have anything to lose, they know us and know how to organise against us."
Nigeria were dangerous down the flanks with Samuel Chukwueze and Alex Iwobi although most crosses were cut out by the Burundi defence. Paul Onuachu was closest in the 14th minute with a header which forced a good save by Jonathan Nahimana.
Nigeria replaced captain John Obi Mikel with Ahmed Musa just before the hour in a bid to add to some speed to the attack but they continued to fail to make the final pass count.
However, one moment of inspiration settled the game. Aina wrong-footed the Burundi defence with his backheeled pass and left Ighalo to place a perfect finish wide of the goalkeeper.
