2012 Africa Cup of Nations champions Zambia were defeated 1-0 in Mozambique on Sunday as their hopes of reaching next year's tournament in Cameroon were extinguished.
After five matches, Chipolopolo sit bottom of Group K on four points, four behind Guinea-Bissau and Namibia in first and second, and three off Mozambique.
The top two played out a 0-0 draw in Windhoek on Saturday.
Reginaldo scored the only goal of the game - in the 63rd minute - as Mozambique secured a major victory to keep their qualifying hopes alive while Zambia were left to rue a miserable qualifying campaign.
Belgian coach Sven Vandenbroeck, who won the 2017 AFCON with Cameroon as part of Hugo Broos's technical team, has wholly failed to build on the momentum Zambia enjoyed under Wedson Nyirenda.
The Southern Africans took eight points from their World Cup qualifying campaign, beating Algeria home and away, while holding Cameroon in both legs, but will now sit out a second consecutive AFCON.
Recently crowned African champions have struggled to qualify for subsequent tournaments; Egypt missed out in 2012 and 2013 after winning in 2010, while Zambia have now missed the last two competitions.
Nigeria, who secured their ticket for the 2019 event with a draw against South Africa on Saturday, are returning to the AFCON for the first time after winning the title in 2013.