Argentina will fancy their chances, having recovered from a shaky opening draw with Syria to almost pip Spain to top spot in Group C. However, to advance further, the defensively-solid South Americans will need to be more clinical in the finishing than they have been thus far at the tournament.
Costa Rica, who also finished runners-up in their section (Group A), have proved one of the revelations of Korea 2007. Without ever compromising their renowned attacking style, the Ticos raised eyebrows during the group stage, most notably with their impressive 2-0 win over hosts Korea Republic. Don't be mislead by their slip-up against Peru in their final group game, Manuel Urena's boys have nothing to lose and are in the mood for an upset.
With no injury concerns, Miguel Tojo will only have to do without defender Alexis Machuca, who serves a one-match suspension after picking up his second yellow card of the group stage against Spain. Costa Rica, for their part, have a full squad to choose from.
Thursday's game will be the fourth meeting between the sides at a FIFA U-17 World Cup. Thus far, the Albiceleste have had it all their own way, winning all three ties without conceding a goal: 2-0 at Ecuador 1995 and again at Finland 2003, and 1-0 at Egypt 1997.
"This is a solid and very tightly-knit group. And even though we don't always play as we'd like, we never stop battling. This team is on the up and making progress, but now we have to play twice as well as I'm sure we're going to make it into the next round." Damian Martinez, Argentina defender
"Now it really gets interesting and we have a good enough team to take on anyone. We know how good Argentina are, but this is what we've been preparing for. Yes, they're a great team, but I'm very confident we can beat them." Roy Smith, Costa Rica defender and captain