Sundowns are currently in Cairo, where they are set to take on the CAF Club of the Century and record eight-time Champions League winners in their quarterfinal first leg on Saturday evening (18h00).
The two sides last met at the same stage of the competition 11 months ago, when The Brazilians walked away 5-1 aggregate winners after taking a 5-0 lead from their home leg tie.
However, Mosimane feels this time circumstances are much different and such a hefty scoreline cannot be repeated, particularly given the present form of The Red Devils.
"It's a tough game for us, with big expectations, of course, but we understand the mood and mentality from last year's results. We know it's not going to be the same," said Mosimane.
"We are facing Ahly at the wrong time. They've been winning everything here – if I'm not mistaken it's been 15 or 16 games [winning streak].
"I think they've scored more than 40 goals, conceded maybe less than five, and even Real Madrid or Barcelona don't have such a record.
"So, that's why we are very cautious, tread carefully and we respect their space. That's where we are.
"I don't know where the pressure is, but if it's on us to repeat the same result then it's not possible. That happened once, it's history, it will never happen again."