AmaZulu missed out on the chance to go top of their group in the Caf Champions League after they suffered a 2-0 defeat to ES Setif at Stade du 5 Juillet 1962 on Saturday night.
Usuthu never looked like getting back into the contest after Riad Benayad broke the deadlock in the 11th minute, with Akram Djahnit sealing the victory on the stroke of halftime.
The DStv Premiership club dropped to third in group B as the Black Eagles leapfrogged them into second place, although both teams are tied on six points going into the final two matches.
Benni McCarthy's side got off to the worst possible start in Algeria as they came under siege from the get-go.
The hosts threatened as early as the opening minute when Zoubir Motrani fired high and wide of the near post after making his way into the box on the left and they hit the front with their next chance on 11 minutes.
Ahmed Kendouci threaded Benayad through on goal and the striker beat Veli Mothwa with a well-placed shot into the bottom left corner of the net from outside the area.
Mothwa denied Benayad a second goal on 25 minutes with a fine save after he managed to get a shot off inside the box from Zoubir Motrani's pass.
Usuthu's best opportunities came from set pieces as Thembela Sikhakhane dragged an effort wide of the left post after connecting with Keagan Buchanan's 29th-minute free-kick before Luvuyo Memela just cleared the crossbar from a dead-ball situation on the edge of the area in the 38th minute.
Mothwa was called into action again on 43 minutes to keep out a long-range strike from Benayad and he pulled off another save from the same player in stoppage time, but Djahnit was on hand to slot home on the rebound.
Two goals up at the break, the Black Eagles quickly got into their stride after the restart and Benayad went close with a strike from range that flew just wide of the left post in the 46th minute.
Bonginkosi Ntuli came even closer at the other end 10 minutes later as his effort from inside the area struck the crossbar, while Tapelo Xoki was unable to keep his header down in the 64th minute after getting on the end of Augustine Mulenga's free-kick.
Moments after Abderrahim Deghmoum directed a header over the target from Kendouci's cross, Ntuli headed wide at the opposite end of the pitch on 75 minutes.
The Algerian giants continued to push for a third goal at the death, but Mothwa stood firm to prevent Abdelhak Debbari and Djahnit from scoring within the space of two minutes.
ES Setif (2) 2 (Benayad 11', Djahnit 45+1')
AmaZulu 0
ES Setif: S. Khedairia, A. Debbari, A. Nemdil, H. Belkaroui (I. Hachoud 74'), H. Ferhani, A. Boutiche, A. Kendouci, A. Deghmoum (M. Bakrar 90+2'), A. Djahnit, R. Benayad, Z. Motrani (I. Farhi 67').
AmaZulu: V. Mothwa, T. Sikhakhane, M. Gumede, T. Xoki, R. Malepe, L. Memela, K. Buchanan (X. Mlambo 68'), M. Makhaula, M. Ceesay (A. de Jong 46'), S. Mthembu (B. Ntuli 46'), A. Mulenga (A. Majok 89').