Guinea-Bissau hit back to defeat Zambia 2-1 in Bissau on Sunday and move closer to a second successive appearance at the Africa Cup of Nations.
Justin Shonga scored direct from a free-kick to put the visiting team into an early lead in a Group K qualifier watched by a capacity 20 000 crowd in the national stadium.
Stoppila Sunzu conceded an own-goal soon after half-time and Toni Silva scored the decisive goal with a header just past the hour.
Guinea-Bissau top the table with seven points from four matches and Namibia and Mozambique, who play in Windhoek Tuesday, and Zambia have four each.
Victory for the tiny Portuguese-speaking state at a ground overlooking the Atlantic Ocean avenged a 2-1 loss in Lusaka four days ago.
They made no impression in the Cup of Nations until qualifying for the 2017 finals at the expense of three other countries, including former champions Zambia.
Guinea-Bissau visit Namibia in November and host Mozambique next March in their remaining fixtures and seem set for a top-two finish and qualification for the finals in Cameroon.
It was Zambia, though, who threatened more in the early stages and Shonga beat goalkeeper Jonas Mendes with a perfectly executed free-kick from the middle of the pitch on 12 minutes.
Guinea-Bissau thought they had equalised after 34 minutes, but Frederic Mendy was judged to have fouled goalkeeper Kennedy Mweene as he nodded a cross into the net.
The home side did draw level on 53 minutes when a Piqueti ‘Brito’ Silva cross was deflected by Sunzu past Mweene at the near post.
South Africa-based Silva struck eight minutes later, powerfully heading a free-kick from captain Jose ‘Zezinho’ Lopes into the corner of the net.
Shonga had a late chance to level, but blazed wide from inside the box to leave Zambia in danger of missing successive Cup of Nations tournaments.
It was the first competitive loss for Belgium-born Zambia coach Sven Vandenbroeck after a draw in Namibia last month and the home win over Guinea-Bissau.
Vandenbroeck assisted compatriot Hugo Broos as they steering Cameroon to the African title in Gabon last year.
In Nairobi, Kenya hammered Ethiopia 3-0 in a top-of-the-table showdown to take a three-point lead in Group F, which is completed by Ghana and Sierra Leone.
Michael Olunga and Eric Johanna scored within four minutes midway through the opening half and Tottenham Hotspur midfielder Victor Wanyama converted a second-half penalty/AFP.