Sundowns have been in Luanda since Tuesday to prepare for their penultimate Group C fixture, having already sealed their spots in the knockout stages of the competition.
Petro, meanwhile, have seen their slim hopes of advancing dashed by Wydad Casablanca, who secured their passage to the next round after beating USM Alger 3-1 on Friday night.
But Mosimane still believes the Angolan champions have pride to play for on their home ground in front of their home supporters, while The Brazilians will show respect and look to suss them out.
"We expect the team here to attack us more than they attacked Wydad Casablanca and USM Alger when they came to play here," said Mosimane.
"I don't know what's the best for us, but sometimes the best form of defence is to attack. So sometimes you can respect the power and force that pushes you back.
"But If we decide to attack, and we do so very well, then it means they have to be careful that we can score. If you sit back, you create more pressure for yourself and play in the hands of the opposition.
"The team knows that if you attack more, you open yourself for counter-attacks. So, it's football, whatever you do has its own advantages and disadvantages.
"We will see what the game is about, but in my heart I feel that the team will attack us a lot."
Kick-off of this afternoon's clash is scheduled for 14h00 (SA time).