Djibouti registered a first international victory since 2007 on Wednesday, when they beat South Sudan at the start of the race to the 2019 Africa Cup of Nations.
They won the game 2-0, at home, to take the lead in their two-legged preliminary round tie.
In the other match, Madagascar beat Sao Tome e Principe 1-0.
The teams are competing for places in the main group phase of the qualifying competition.
Djibouti broke their long running barren spell thanks to goals from Hamza Abdi Idelh and Med Salam.
An overall win will take them into Group C in the race for Cameroon 2019, where they will face Burundi, Gabon and Mali.
It was a fine start for new Mauritanian coach Moussa Ghassoum, who was taking charge of his first match with the team.
South Sudan continue their dismal away record - having lost all their matches on the road in qualifiers, scoring just once and conceding 15 goals.
There were two new coaches on display in Wednesday's other match, as Frenchman Nicolas Dupuis earned a win in his first game in charge of Madagascar, against Gustavo Clemente's Sao Tome.
An own goal from Sao Tome's Jordao Diogo gave the Malagasy the win.
The winner of the tie will head to Group A with Equatorial Guinea, Senegal and Sudan.
Madagascar had several key players out injured but still a strong squad and flew players from European clubs directly to Sao Tome to save money, supplementing them with a home-based contingent.
The third preliminary round tie was an Indian Ocean derby between the Comoros Islands and Mauritius, with the first leg in Moroni on Friday.
Comoros came out on top 2-0, giving them a healthy advantage for the return game at the Stade Anjalay at Pamplemousse on Tuesday, 28 April.