Former champions Asante Kotoko of Ghana and Cameroon's fabled Canon Yaoundé were both eliminated from the competition at the hands of unfancied opposition, but it was the unheralded AS FNIS of Niger who crated the biggest shock.
Their 2-0 home win over USM Alger confined the Algerian side to yet another early exit in the Champions League, snatching the tie on the away goals rule. FNIS are the first side from the arid Saharan country to take a major scalp in continental club competition .
It was the last-minute goal scored by Hamidou Djibo in the first leg that set up the unlikely victory. USM Alger had been 3-0 up in the match before Djibo's consolation effort - but it proved a vital touch and the home side scored twice without replay in Sunday's second leg in Niamey for a rare fillip for football in Niger.
Kotoko were knocked out on penalties by Gambia Ports Authority at the end of their second leg game in Banjul on Sunday.
The Ghanaian giants, who went into the game with a cloud over the head of their Turkish coach Telat Uzum, had a slender 1-0 lead from the first leg, played in Obuasi last weekend.
In the return, Kotoko held out until the 80th minute when a misunderstanding between goalkeeper Isaac Amoako and defender Dan Acquah allowed GPA substitute Alagi Musa Camara to sneak in and score.
That forced a 1-1 aggregate draw and necessitated a penalty shootout, which the home side won 4-2.
The Gambians had been reinforced by five players from the national under-20 side who had missed the first leg because of commitments at the African youth championship in Congo, which ended earlier this month and at which Gambia secured third place to book a trip to the FIFA World U-20 Cup in Canada later this year.
Despite the celebration of a major scalp, the home side's coach Alhaji Sarr felt the margin of victory could have been bigger: "We squandered numerous scoring chances in the first half, because my boys were bit panicky, knowing that only a win would save us after our 1-0 (first leg) defeat in Ghana."
Shocks and surprises
Canon, seeking this year to return to their preeminent position in African football, were beaten 2-0 away in Brazzaville by Etoile du Congo and went out 2-1 on aggregate. Eder Lebaly scored twice in the space of four minutes midway through the first half to turn the formbook on its head.
The likes of Togo's Maranatha Fiokpo, Gabon's MangaSport, FC Kallon of Sierra Leone and APR FC of Rwanda also went through to the second round by beating more fancied opposition.
The Rwandese army club won both home and away against FC St Eloi Lupopo of the Democratic Republic of Congo, their win having been engineered by coach Andy Futila, who until just a few months ago was working at the helm of the Lubumbashi-based club.
Maranatha beat Diaraf Dakar of Senegal 3-0 in Lome on Sunday to easily turn over a one-goal deficit from the first leg. An early penalty from Ayi Assiongbo was followed by two second-half goals by Mani Sapoul and Léonard Adjima.
MangaSport held out for a 1-1 home draw to beat off an attempted comeback from Angolan champions Primeiro Agosto.
FC Kallon eliminated the Nigerian champions Ocean Boys, scoring the only goal of their tie in Sunday's second leg in Freetown.
The biggest win of the weekend was registered by AS Adema from Madagascar, who were held to a goal-less draw at home in the first leg of their tie against fellow Indian Ocean islanders Anse Reunion from the Seychelles.
But in the return in Victoria on Saturday, the Malagasy side earned a 3-0 triumph and now play two-time continental champions TP Mazembe Englebert of the Democratic Republic of Congo in next month's second round.
The second-round draw:
Highlanders (Zimbabwe) v Al Ahli (Egypt)
Desportivo Maputo (Mozambique) v Mamelodi Sundowns (South Africa)
Al Hilal (Sudan) v Zamalek (Egypt)
Nasarawa United (Nigeria) v Port Authority (Gambia)
Fello Star Labe (Guinea) v Etoile Sahel (Tunisia)
APR FC (Rwanda) v Maranatha Fiokpo (Togo)
Al Ittihad (Libya) v AS FNIS (Niger)
St George (Ethiopia) v Etoile du Congo (Congo)
AS Douanes (Senegal) v Wydad Casablanca (Morocco)
FC Kallon (Sierra Leone) v ASEC Abidjan (Cote d'Ivoire)
Young Africans (Tanzania) v Petro Atletico (Angola)
Esperance (Tunisia) v ZANACO (Zambia)
AshantiGold (Ghana) v Royal Armed Forces (Morocco)
AS Adema (Madagascar) v TP Mazembe Englebert (DR Congo)
Mangasport (Gabon) v JS Kabylie (Algeria)
Sewe Sport (Cote d'Ivoire) v Coton Sport (Cameroon)
Teams mentioned first play at home in the first legs on the weekend of 2-4 March. The return legs will be played on the weekend of 16-18 March.