The Brazilians are at home to the side from Guinea in their final Caf Champions League Group C clash which has become a must-win game if they hope to progress in the tournament.
“We are used to situations like this, absorbing pressure. We have a good mentality going into this game - we have enough ammunition,” Mosimane told reporters on Monday.
“It's a must-win at all costs. They have a tough goal minder (Khadim Ndiaye) to beat and it will be tricky because they have a good attack also,” he added.
The Brazilians' boss is yet to find the right combinations upfront after parting ways with strikers Percy Tau who joined Brighton & Hove Albion in England and Khama Billiat who moved to Kaizer Chiefs.
However, Mosimane has signed the likes of Jose Ali Meza, Toni Silva and Lebohang Maboe to bolster his attacking options, but says it will take time before they find their feet.
“We're trying to get a working formula. Please give us a chance guys, we lost key players from the previous campaign,” Mosimane expressed.
“We are building, be patient, but we always score here (Lucas Moripe Stadium)...we're hoping to continue that trend. One goal win should be enough,” he reacted.
'Jingles' also said they have a responsibility of flying the South African flag in the continent as they are the only Premier Soccer League (PSL) currently playing in Caf club competitions this year.
“We mustn't drop the flag, we have a responsibility of flying the South African flag high, we will do that,” he concluded.
The current PSL winning coach also revealed that defender Bangaly Soumahoro is now back after having knee problems but will be unavailable for the encounter.
Meanwhile, Sundowns have five points as they sit in third place in the group whilst Horoya occupy second spot with eight points. A draw will be enough for the visitors to reach the knockout stages.