Burkina Faso forward Bance, 35, a standout figure with his huge build and dyed blond hair, helped Horoya to a 4-2 home victory over Bandari of Kenya after a seesaw struggle in Conakry.
Horoya were ahead within a minute of the kick-off and scored a second goal before Bandari fought back to be level at 2-2 by half-time.
Bance, whose nomadic career includes spells with 22 clubs in Africa, Europe, the Middle East and Asia, netted twice during the second half for the multi-national Guinean team.
Horoya are bankrolled by Antonio Souare, a businessman who has pumped millions of dollars into the club in pursuit of African glory.
They reached the CAF Champions League quarter-finals in the past two editions, but were ousted in the final qualifying round for the 2019/2020 group phase.
This triggered demotion to the second-tier Confederation Cup -- the African equivalent of the UEFA Europa League -- as they seek a second CAF title after winning the 1978 Cup Winners Cup.
While Bance is an old school centre forward skilled at using height and physique to translate crosses into goals, Tembo, 34, operates as a central defender, making his feat special.
The hat-trick earned Zanaco a 3-1 win over Cano Sport Academy of Equatorial Guinea in Malabo, where a floodlights failure temporarily halted play during the second half.
Tembo scored either side of half-time to give the Lusaka outfit a two-goal advantage and he completed the scoring 11 minutes from time after Jose Fidel Sipi had halved the deficit.
- Mixed Nigerian fortunes -
Nigerian contenders had mixed fortunes with Enyimba overcoming South African second division side TS Galaxy 2-0 in Aba while Enugu Rangers fell 2-1 away to ASC Kara of Togo in Lome.
Twice African champions Enyimba ended a four-match winning CAF streak by Galaxy thanks to goals from Victor Mbaoma on seven minutes and Martins Usule after an hour.
Galaxy, who qualified by stunning Kaizer Chiefs in the domestic cup final, impressed with an adventurous approach and had a first-half goal disallowed for offside.
A stoppage-time goal from Richard Nene brought Kara victory over Enugu, whose lone continental triumph came 42 years ago in the now defunct African Cup Winners Cup.
Kenyan club Gor Mahia were held 1-1 in Nairobi by Daring Club Motema Pembe of the Democratic Republic of Congo after a dramatic clash of two other former Cup Winners Cup trophy-holders.
Gor took a second-half lead that lasted just eight minutes, goalkeeper David Mapigano saved a penalty, and they finished with 10 men because Charles Momanyi was red-carded.
Big-spending Egyptian side Pyramids built a 2-1 lead away to Young Africans of Tanzania in lakeside city Mwanza through goals from Burkinabe Eric Traore and Abdallah el Said.
Fosa Juniors of Madagascar upset 2018/2019 Confederation Cup runners-up Renaissance Berkane of Morocco 2-0 in the Indian Ocean island with the second goal coming from a stoppage-time penalty.
A scoreless match between Asante Kotoko of Ghana and San Pedro of the Ivory Coast will be completed Monday after being abandoned at half-time due to a waterlogged pitch.
The second legs are scheduled for November 1-3 with the aggregate winners advancing to a November 10 group draw in Cairo.