Costa Rica (5 million population) is a rocky, rain forested Central American nation with coastlines on the Caribbean and Pacific.
Los Ticos made it all the way to the quarter finals in the last 2014 World Cup, despite playing in a group with three former World Cup Champion Nations.
Led by head coach Oscar Ramirez, Costa Rica are very confident that can do better in Russia in what may be the last World Cup for players like Keylor Navas, Christian Bolaños and Bryan Ruiz.
The best and the most famous player of Costa Rica is certainly Real Madrid keeper Keylor Navas, 31 year old. With his great saves he can make the difference in many games at World Cup.
Another key player to watch is forward Joel Campbell (25 year old) that plays for Real Betis. He’s versatile and can play forward but can also be used on the wings.
Please see here the full 23-man squad of Costa Rica
Serbia is a fantastic nation with 7 million population situated on Eastern Europe with northern plateaus and mountains with ski resorts to the south.
Their Best Player is Man United midfielder Nemanja Matic 29 years old. The vice-captain has strong shoot, quick passes and can cover successfully both phases, attack and defense.
Another key player to watch is striker of Fulham FC Aleksandar Mitrovic 23 years old. He’s strong, agile, creative and scored 12 goals in 19 appearances for Cottagers (Fulham FC) that just promoted back onto Premiere League.
Finally Serbia got a strong and experiences defense with Aleksandrar Kolarov and Branislav Ivanovic that can lead the defense to perfection.
Please see here the full 23-man squad of Serbia