Gelson Dala raised his Africa Cup of Nations goal tally to four with a brace for 10-man Angola in a 3-0 last-16 triumph over Namibia in Bouake on Saturday.
Surprise package Angola will face Nigeria or Cameroon, who meet later in Abidjan, in a quarter-final next Friday.
After Dala scored twice in the first half, Mabululu netted midway through the second half to effectively end as a contest the clash of southern Africa neighbours.
Both teams were reduced to 10 men by first-half red cards with Angola goalkeeper Neblu and Namibia defender Lubeni Haukongo sent off.
The winning margin was a record for Angola, bettering two-goal victories over Senegal and Malawi in previous Cup of Nations.
The first of eight second-round fixtures was not one that would have been anticipated when the African football showpiece kicked off in the Ivory Coast 14 days ago.
Angola won a group ahead of Burkina Faso, Mauritania and shock casualties Algeria when they were expected to finish third at best given an AFCON record of just four victories in 26 matches.
The best Namibia had managed in three previous appearances was two draws while losing seven other matches. One of the draws was against Angola in Burkina Faso 26 years ago.
Angola, showing two changes from the team that started a win over Burkina Faso last Tuesday, were reduced to 10 men after just 17 minutes.
– Searing heat –
Neblu — one of many Angolans who use a nickname rather than their real name — handled a Bethuel Muzeu lob outside his area and was immediately red-carded.
Reserve goalkeeper Antonio Dominique came off the bench at the expense of midfielder Estrela and was quickly brought into action as he parried to safety a Deon Hotto free-kick.
After a water break to assist players performing in searing 34 degrees Celsius (93 Fahrenheit) heat, the match took a dramatic turn with two goals and another red card in four minutes.
A Gilberto cross and Fredy cutback set up Dala to sidefoot the ball into the corner of the net on 38 minutes.
Namibia surrendered their numerical advantage two minutes later when Haukongo was yellow-carded a second time and sent off by the Mauritanian referee.
Dala struck again on 42 minutes, powerfully heading a Fredy free-kick into the corner of the net to give Angola a two-goal advantage they retained until half-time.
After early second-half pressure from Namibia as they sought the goal that bring them back into contention for a last-eight place, Angola stretched their lead to three goals on 66 minutes.
Having fired narrowly wide, veteran Mabululu almost instantly atoned by sprinting on to a Dala pass before superbly curling a shot past goalkeeper Lloyd Kazapua.
The unquenchable spirit of the Namibians in the face of a looming loss was demonstrated in the closing minutes when a Riaan Hanamub shot forced a spectacular save from Dominique.
In added time, Angola were denied a fourth goal when a shot from substitute Zito Luvumbo rebounded off the crossbar.