What's on the line
The round of 16 match in Pretoria, South Africa pits two nations that are each appearing in a fourth straight World Cup. Yet, with neither Japan nor Paraguay ever having reached the final eight, that means the winner will move on to its first-ever World Cup quarterfinal, where it will face the survivor of the Spain-Portugal encounter.
Style and tactics
As evidenced in the group stage when it allowed just one goal in three games, Paraguay remains a traditionally solid side with a cohesive defensive unit. The Albirroja could line up in a 4-4-2 formation or utilize a 4-3-1-2 setup; and while manager Gerardo Martino usually opts for a more conservative system, he has begun to instill more of an attacking mindset to initiate opportunities for his talented forwards.
Japan relied on its pace and a packed midfield to thwart opponents in the opening round, when it defeated Cameroon and Denmark. Marcus Tulio Tanaka and Yuji Nakazawa provide experience in defense for the Blue Samurai, while veterans Yasuhito Endo and Makoto Hasebe control things in the midfield.
Players to watch
Keisuke Honda, Japan. The CSKA Moscow player has become one of the stars of this World Cup, scoring in both of his team's wins and serving as his side's creative spark while offering assistance in attack to compensate for Japan's lack of a strong center forward.
Nelson Haedo Valdez and Lucas Barrios, Paraguay. Paraguay's forward line has not scored one goal in South Africa. And with Roque Santa Cruz and Oscar Cardozo failing to fire thus far, the scoring punch could be provided by Valdez and Barrios -- teammates at Borussia Dortmund who enjoyed strong seasons in the German Bundesliga. The 25-year-old Barrios was only recently cleared to play internationally for Paraguay, and has contributed a goal in each of his first two appearances in World Cup warm-ups.
What we can expect
This knockout match could be a tight affair with both sides taking a cautious-but-determined approach, with extra time possibly required between the two evenly matched teams. Japan has used the same 11 starters in all three games during group play, which can either prove to be a positive by creating a more cohesive unit, or mean that tired legs could potentially let the team down in an extended, 120-minute affair.
Can Paraguay's "round of 16 hex" be broken in 2010? The South American side reached the second round at the 1986, 1998 and 2002 World Cups but has never advanced beyond the Round of 16. With a solid team, capable scorers and a decent World Cup draw, will this be the year that the Albirroja finally reach the quarterfinals?
Yes, this will mark the first time in the final eight for Paraguay, as a 1-0 victory over Japan allows the Albirroja to join the South American party being staged in South Africa -- with CONMEBOL providing half of the tournament's final eight teams.
Michael Griffin is an editor for ESPN.com.