The Bamako-based side suffered a disappointing 3-0 defeat in the first-leg quarter-final at Loftus Versfeld Stadium.
Despite a bright start in Pretoria, the Brazilians took control when Khuliso Mudau opened the scoring in the 33rd minute, finishing from close range after a delivery from Arthur Sales.
Brayan Leon added a second shortly after the break, before substitute Iqraam Rayners sealed the win late on.
Although the South Africans hold a strong advantage going into the second leg on Sunday evening, the former Stade Malien star insists a comeback cannot be ruled out inside Stade du 26 Mars.
"We (Stade Malien) gave everything in their first-leg clash against Mamelodi Sundowns, but things did not go according to plan as three goals were conceded," Diawara told Flashscore.com.
"Honestly, the result came as a surprise, especially when you consider how solid they have been defensively throughout the tournament.
"Despite the setback, the spirit within the camp remains strong. If Sundowns were able to score three goals on their home soil, there is every reason to believe we can respond in kind.
"No doubt, it will not be easy against such a strong and experienced South African side, but all hope is not lost.
"There is a firm sense of determination among the players and during the week, I spoke with the coach and some players and they fully understand what is at stake and are ready to fight back like a wounded animal."
The CAF Champions League title has long eluded the Malian side and when Diawara was asked whether this current team could finally break that jinx if they manage to overcome the South Africans, he added: "Football is not decided by predictions but by what happens on the pitch.
"Stade Malien are a strong side, but it may be too early to talk about title chances with such a crucial match ahead.
"Even if we manage to get past Mamelodi Sundowns, each game must be taken seriously remain disciplined and respect every opponent, and approach each game with the right mindset.
"Only by doing so can they stay on track and give themselves the best chance of making history for themselves and bringing joy to the people of Mali."
On the other side, coach Miguel Cardoso has urged his Mamelodi Sundowns players to guard against complacency, despite holding a three-goal advantage.
The Portuguese stated that football can be unpredictable and warned his side not to take anything for granted ahead of the second leg.
"Champions League is an open game. I was taking a look, Sporting Portugal lost 3-0 in the first leg of the conference league and in the extra time was winning 4-0 at home.
"So, football shows us everyday stories that can be done and changes of games that can be done. We cannot think things are done; they should be controlled by us. So, the Champions League is not a story that is written yet."
