The game is scheduled to kick off at 3pm South African time.
"We do not need anyone to remind us or push us to the limit with regards to the importance of this game. We know its massive significance," said the stocky striker.
The match is a potential group decider as Ethiopia have ten points and South Africa eight, with two rounds left.
A win for the home side would give them an unassailable advantage over South Africa.
"It is not like there is a choice here -- either we swim or sink -- it is as simple as that.
"This for us is like playing a cup final because we know anything less than victory will be irrelevant."
He said Bafana Bafana would draw lots of positives from their 3-0 victory over Central African Republic last week. The team overcame the trials and tribulations of cancelled flights and risky overnight bus rides leading up to the match, which was played in the neutral city of Yaounde, Cameroon.
The South Africans remained there to prepare for Sunday's crucial encounter.
"On Tuesday we watched the video of Ethiopia's match against Botswana and we noticed some areas where we feel we can capitalise on and win on Sunday," Rantie said.
"They are a strong side, no doubt about that, and they will be playing at home so they should be high on confidence -- which of course, might be their biggest undoing."
Rantie believed team effort combined with individual brilliance would see Bafana Bafana through against the Walia Antelopes.
"As strikers we need to score goals and we have been very hard at training working on that.
"I am confident though that we are going to win on Sunday; I have that gut feeling."
Bafana Bafana would have their last training session in Yaounde, Cameroon on Wednesday, with Thursday set aside for travelling to Douala before flying out to Ethiopia on Friday.