Mashaba's men need a victory to have any chance of progressing to the AFCON quarter-finals, as they sit bottom of Group C with just one point.
Senegal lead Group C with four points, while second-placed Algeria and Ghana, who are third, both have three points.
For South Africa to reach the last eight in Equatorial Guinea they must overcome Ghana and hope Algeria lose to Senegal, but although his team have conceded four goals in two games, Mashaba insisted they must maintain their attacking focus.
"We used to concede very early in the game but we worked on that, it's changed now towards the dying minutes of the game, that's where our concentration and focus lapses," the 64-year-old coach said.
"And of course, we're looking at working on that. But the biggest thing is, during those periods, we're creating a lot of chances.
"You'll find that could be one of the things - if you don't take your chances, you're going to be punished.
"If you look at the goals that the opposition scores, [they are] soft goals, yeah. And we work to score hard but they always get soft goals. But I think we'll rectify that, wait till tomorrow evening."
Captain Dean Furman argued that South Africa will prove their critics wrong and advance to the AFCON's knockout stage, as they have a history of springing surprises.
South Africa topped their qualification group for the continental championships, eliminating regular contenders Nigeria by remaining unbeaten on the road.
"We've been proving people wrong since the start of this group," the Doncaster Rovers midfielder said.
"No-one expected us to go and win games away in Africa, everybody expected Nigeria to cruise through our qualification group - they struggled, they went out - we went and won games away.
"So we know as a team that we can cause upsets and prove people wrong, and this tournament has shown that the tournament's open for anyone."
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