Spain's kids tackle experienced Costa Rica

The young Spain players at the heart of coach Luis Enrique's new-look side make their debut on the global stage when they face the veterans of Costa Rica in their Qatar World Cup opening match.

With captain Sergio Busquets the lone survivor of the Spain team that won the 2010 tournament in South Africa under then coach Vicente del Bosque, Luis Enrique has blooded a new generation of players in preparation for Qatar.

Three years into the restructuring of the national side after dismal showings in Brazil in 2014 and Russia four years later, there are signs the former Barcelona and Real Madrid star is building something that will be a force for years to come.

Barcelona's midfielders Pedri (19) and Gavi (18) and forward Ferran Torres (22) are three of the young guns in the fresh-faced Spain side.

Luis Enrique - who led the Spanish to the semi-finals of the Euros last year where they were eliminated by Italy on penalties - has picked 14 players aged 25 or under.

The average age of the squad is the third youngest among the 32 teams in Qatar.

"We are a team with a lot ahead of us, we are very young," Torres said on Sunday.

Asked whether he felt the team was obliged to prove themselves by finishing in a strong position in the tournament, Torres stressed Spain remain a work in progress.

"We're not obliged to finish in any place. We will simply play the best we can to get results and if we can we will keep going.

"If we don't get the results, we will go out with our heads held high and keep working. We are young."

For Costa Rica, playing in their sixth World Cup, the picture is almost the complete opposite.

Six of their squad members were part of the 2014 campaign - when the team qualified from a 'group of death' at the expense of Italy and England - all of them now aged 30 or over, including striker Bryan Ruiz who is 37.

Colombia coach Luis Fernando Suarez's team are known for their solidity - they conceded only eight goals in qualifying - and for their ability to counter-attack swiftly and dangerously.

But the age of some of Costa Rica's core players may pose challenges beyond the physical demands of the game - goalkeeper Keylor Navas, for example, has not played a competitive game for his club Paris St Germain in five months after losing his place to Italy's Gianluigi Donnarumma.

Spain and Costa Rica, who are in Group E along with Germany and Japan, do battle at Doha's Al Thumama on Wednesday (3am Thursday AEDT).