#4 Uruguay: 66 appearances
Uruguay have always gone into the World Cup as dark horses. A small South American country with less than 4 million people, they have done well to produce and develop footballers capable of competing on the world stage.
Although La Celeste did not qualify for the 2006 World Cup in Germany, they made their presence felt in 2010 in South Africa and 2014 in Brazil.
The two-time champions (way back in 1930 and 1950) finished fourth in 2010 but they were disappointed when they made a Round of 16 exit in 2014.
Uruguay also have four players who have made at least 100 appearances. Defenders Maxi Pereira and skipper Diego Godin are their most experienced campaigners while midfielder Cristian Rodriguez and Edinson Cavani have reached a century of caps.
Luis Suarez (97), too, will make 100 appearances when he plays in the group stages of the World Cup. Other experienced players include goalkeeper Fernando Muslera and defender Martin Caceres.
The average age of Uruguay's squad is 28 years and 47 days.