Midfielder Karim Aouadhi scored the only goal as Sfaxien, three-time winners of the second-tier continental club championship won 1-0 in regulation to make it 1-1 on aggregate, forcing the tie to penalties.
However, Aouadhi metamorphosed from hero to villain failing to convert his penalty, blasting wide, which cost his team a place at the semis of the competition.
The game headed for penalties which saw Badr Boulhroude, Lamine Diakite, El Mehdi El Bassil, Zakaria Benlamachi and Mohamed Saoud scoring for FUS Rabat against Meriah Yassine, Hamza Mathlouthi, Ala Marzougui and Oussama Amdouni for Sfaxien.
FUS Rabat will face either holders TP Mazembe of DR Congo or Sudanese debutants Hilal Obeid at the last four.
22.09.2017 Sfax CS Sfaxien (Tunisia) 1-0 (4-5pen) FUS Rabat (Morocco)(0-1)
23.09.2017 Ndola Zesco (Zambia) vs Supersport (South Africa) (0-0)
24.09.2017 Tunis Club Africain (Tunisia) vs MC Alger (Algeria) (0-1)
24.09.2017 Lubumbashi TP Mazembe (DR Congo) vs Hilal Obeid (Sudan) (2-1)