The Super Eagles must beat Ethiopia at the Royal Bafokeng Stadium on Tuesday to ensure their progression from Group C, with previously unfancied Burkina Faso and reigning champions Zambia occupying the top spots going into the third round of group games.
Nigeria were held to draws by both nations and Keshi remains wary of Ethiopia's potential to spring a surprise, especially considering Cape Verde's shock win over Angola on Sunday night.
He told Nigerian newspaper Vanguard: "I am very impressed with what I have seen so far. You can no longer differentiate so much between which teams are better.
"In the old days you could predict how many goals one team was going to score against the other but now you don't know what is going to happen.
"You might think one side will win but you don't know. I think this is wonderful for African football.
"The competition is so tight, you look at the likes of Ethiopia and Cape Verde and some of the other countries. I am very impressed with their performances and the standard they are reaching."
Ethiopia returned to the showpiece tournament for the first time since 1982 and gave themselves a slim chance of a quarter-final place by claiming a 1-1 draw with Zambia.
A 4-0 defeat to Burkina Faso followed, though, and coach Sewnet Bishaw knows the goals have to flow against Nigeria if the Antelopes are to turn the mathematics in their favour.
He told Vanguard: "We hoped that we would play again like the first game and take a point against Burkina Faso.
"We're not going on to the field to defend, because defending will only give you one point. Now we must try to play against Nigeria to score goals and get three points.
"If we get three points, in total we'll have four, and may qualify for the next stage.
"Not only will we just score one or two goals, we need to score lots of goals, otherwise it is a matter of dignity for our boys."