What's on the line
The victor of the Germany-Argentina encounter awaits the winner of this game, a matchup between a team that has never won a quarterfinal in four previous appearances (Spain), and a team playing in its first-ever quarterfinal (Paraguay). With Spain sitting second in FIFA's latest world rankings -- 29 places ahead of Paraguay -- this is the biggest disparity between teams playing in this Cup's quarterfinals. The winner will reach the World Cup semifinals for the first time in its history.
Style and tactics
Having allowed just one goal in four games during this tournament, 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; manager Gerardo Martino has opted to play conservatively throughout the World Cup. Paraguay has a number of talented forwards in Roque Santa Cruz, Lucas Barrios and Oscar Cardozo, but none has scored a goal yet in South Africa.
Spain is a team that controls possession and relies on its passing game and clever through balls to set up scoring chances. Carles Puyol and Gerard Pique form a solid partnership at the back, while Xavi Hernandez and Andres Iniesta control things from the midfield. With striker Fernando Torres not showing top form in South Africa, it will be interesting to see how long coach Vicente Del Bosque leaves the Liverpool man on the pitch if he continues to struggle against Paraguay.
Players to watch
Justo Villar, Paraguay. Having spent the past two seasons with Spanish club Valladolid, the Paraguay goalkeeper will be familiar with most of the Spain team. Villar and his dependable defense have recorded three straight clean sheets in South Africa, but haven't yet faced the type of attack that their quarterfinal opponent possesses.
Xavi Hernandez, Spain. The team's midfield general started slowly against Switzerland but has picked up his game since the opener, and his crafty back heel put David Villa in position to score the lone goal against Portugal. With his side expected to have most of the possession in this match, he could again play a role in determining its outcome.
Roque Santa Cruz, Paraguay, and Fernando Torres, Spain. Both of these Premiership strikers have performed poorly in the World Cup, with neither yet registering a goal. Each was taken off during the second half of his round of 16 match, yet should be given another chance to break out in the quarterfinal encounter.
What we can expect
This knockout match should see Spain controlling possession against a Paraguay team content to sit back in defense. Facing a bunkering opponent is a situation the Spaniards have seen all tournament, and their exciting attack has been subdued at times. Paraguay has not allowed more than one goal in any of its past nine World Cup games -- since it lost 3-1 in 2002 to Spain, coincidentally -- and will look to counter through Santa Cruz, Barrios and Nelson Haedo Valdez.
All the pressure is on Spain to advance from this match, since the reigning European champions came into the World Cup as one of the favorites. The Spaniards have never made it to the semifinals, although they did make the final group of four teams at the 1950 tournament in Brazil (when round-robin play among the remaining participants determined the final outcomes and places). With a reputation of underachieving in major competitions, is this the year that Spain sheds that tag as it pushes on toward a second trophy in three years?
Most expect Spain to have a relatively easy path to the semifinals, but this writer will go against the grain and predict that Paraguay will be able to hold the Spaniards to either a 0-0 or 1-1 draw after 120 minutes, leaving the survivor of this quarterfinal to be determined by a penalty shootout.
Michael Griffin is an editor for ESPN.com.