2-1 on aggregate having won by that scoreline in east Africa last week.
Botswana clubs have been perennial strugglers in both CAF club competitions, making the progress of Rollers all the more remarkable.
Horoya exceeded expectations by winning 2-0 away to Generation Foot of Senegal in a west African showdown having battled to succeed by a single goal at home.
A Daouda Camara penalty midway through the first half put Horoya ahead and a late goal assured the Conakry club of a place in the group draw next Wednesday.
Another three clubs, Gor Mahia of Kenya, Port of Togo and Rayon Sports of Rwanda, hope Sunday to become the first clubs from their nations to reach the mini-league stage.
Defending champions Wydad Casablanca of Morocco were comfortable overall winners despite a 2-0 away loss to Williamsville of the Ivory Coast.
Goals late in each half from Romuald Kouassi and Kouame Diallo gave the Ivorians victory, but they faced a hopeless task after being trounced 7-2 in Morocco.
Record eight-time title-holders and 2017 runners-up Al Ahly of Egypt triumphed 3-1 away to Mounana of Gabon after taking a four-goal advantage to central Africa.
Mido Gaber, Moroccan Walid Azaro and Walid Soliman netted for the Cairo "Red Devils", who clinched a 40th Egyptian title this week with six matches to spare.
TP Mazembe, the second most successful club in all CAF competitions behind Ahly, scraped through after a shock 3-0 hiding by Songo in Mozambique.
Leading 4-0 after the first leg, the multi-national outfit based in Lubumbashi fell behind in the first minute when Helder Pelembe scored.
An Issama Mpeko own-goal doubled the lead of newcomers Songo, who scored again through South African Rotshidzwa Muleka in stoppage time.
Primeiro Agosto reached the group stage for the first time since 1997 by edging Wits of South Africa 3-2 in a Johannesburg penalty shootout after both clubs won 1-0 at home.
Geraldo, who scored the first-leg winner, converted the decisive spot-kick, calmly stroking the ball into the net after Wits goalkeeper Darren Keet screamed at him.