Real Madrid vs Barcelona

To get an idea of how ridiculously loaded both of these teams are, check out the pedigree of the starting lineups:

For Real Madrid-

GK Iker Casillas - Started all 7 games for 2010 World Cup Champion Spain
DEF Ricardo Carvalho - Started all 4 games for Portugal in 2010 World Cup
DEF Raul Albiol - On World Cup Roster for Spain in 2010 World Cup, did not play
DEF Marcelo - Member of Brazilian National Team
DEF Sergio Ramos - Started all 7 games for 2010 World Cup Champion Spain
MID Pepe - Started 2 games for Portugal in 2010 World Cup
MID Xabi Alonso - Started all 7 games for 2010 World Cup Champion Spain
MID Sami Khedira - Started all 7 games for 3rd Place Germany in 2010 World Cup
FWD Cristiano Ronaldo - Started all 4 games for Portugal in 2010 World Cup
FWD Karim Benzema - Member of French National Team
FWD Angel Di Maria - Started 4 games for Argentina in 2010 World Cup

For Barcelona

GK Victor Valdes - On World Cup Roster for Spain in 2010 World Cup, did not play
DEF Gerard Pique - Started all 7 games for 2010 World Cup Champion Spain
DEF Carlos Puyol - Started all 7 games for 2010 World Cup Champion Spain
DEF Adriano - Member of Brazilian National Team
DEF Dani Alves - 5 appearances (3 starts) for Brazil in 2010 World Cup
MID Sergio Busquets - Started all 7 games for 2010 World Cup Champion Spain
MID Andres Iniesta - Started  6 games for 2010 World Cup Champion Spain
MID Xavi - Started all 7 games for 2010 World Cup Champion Spain
FWD David Villa - Started all 7 games, scored 5 goals for 2010 World Cup Champion Spain
FWD Lionel Messi - Started all 5 games for Argentina in 2010 World Cup
FWD Pedro - 5 appearances (2 starts) for 2010 World Cup Champion Spain

So, between the 22 starters, 17 started in the World Cup, 2 more were on World Cup rosters, and the other 3 have National Team experience for either France or Brazil. There's a reason these are arguably the two best teams in the world right now.