No one is tipping Group A winners Uruguay or Group B runners-up South Korea to get anywhere near the final but their early form has come as a surprise to many teams who could easily have seen them as first-round fodder.
A place in the quarter-finals would mark a stunning turnaround in the World Cup fortunes for either side.
While the likes of World Cup winners Brazil, Germany, Argentina and Italy remain a force in the global game, twice champions Uruguay are a shadow of their former selves having not reached the last eight since 1970 when they were semi-finalists.
Like Uruguay, who are appearing in their 11th finals, South Korea are World Cup regulars but have only advanced from the group phase once, as hosts in 2002 when they made the semis.
The modest Koreans normally play down their chances and speak only about the next game but coach Huh Jung-moo said they were in a hungry mood and looking beyond the second round.
KOREA CONFIDENT
"I know my players will not be satisfied with just reaching the round of 16 and we will work harder to reach the semi-finals," said Huh.
"My players will be shooting for higher targets now."
South Korea's performances have matched their bullish rhetoric, with passing flair, confident breaks and lung-busting fitness, but six goals conceded in their last two matches are glaring reminders of their fragility at the back.
In contrast, Uruguay have yet to concede a goal and have to be the favourites to win in Port Elizabeth on Saturday after their two wins and a draw earned them top sot in the group for the first time since the 1950 World Cup which they won.
Uruguay are expected to stick by a winning formation in which influential striker Diego Forlan has played behind forwards Luis Suarez and Edinson Cavani, a fearsome combination to throw at a so far shaky South Korean defence.
Midfielder Diego Perez said their focus would be to maintain their insatiable appetite for attack but tighten their defence against a dangerous and free-flowing Korean side once again carrying the hopes of the world's most populous continent.
"We are clear that we cannot give away any advantage at all. We know our limits. We know we are strong in defence and we have a good attack," Perez told Reuters.
"It has been long time since things have gone this way. We know we are on a good road," he added. "We must enjoy it."
