The attention of the World Cup usually centers on a few teams-the host nation, the defending Champion and the other top contenders. This particular tournament is special because it may see the end of an era. The end of the Spanish empire.

Spain enters the tournament as the defending champion looking to extend its historic run of trophies. The dynasty started in 2008 when it won the Euro Cup; its first major feat after decades of futility. Two years later, the team managed to triumph in South Africa and take the World Cup. In 2012, the team entered the Euro Championship with a lot of questions. The attacking had lacked the flair of previous years and many wondered how Spain's veterans, which had played during every summer from 2008 through 2012 (with the exception of 2011), would hold up. Spain got off to a slow start in that tournament and then wound up trouncing Italy 4-0 in the final.

Coach Vicente del Bosque likely has some players from those past exploits that he will call upon: Iker Casillas, Pepe Reina, Victor Valdes, Xavi, Xabi Alonso, Sergio Busquets, Andres Iniesta, Gerard Pique, Pedro, David Silva, Jesus Navas, Sergio Ramos, Jordi Alba, Javi Martinez, Alvaro Arbeloa, and Cesc Fabregas. One might make the claim that out of the 23-man squad that del Bosque is allowed to take, 16 players are essentially locks for the squad. Looking back at this list it is clear that goaltending is already accounted for. There are four defenders on this list, nine midfielders and no forwards.

So who are the contenders to join Spain's roster this summer?

Defense

For the Confederations Cup, del Bosque elected to take Raul Albiol, Cesar Azpilicueta and Nacho Monreal as the additional defenders. All of them have chances to return to the squad for the upcoming tournament. Azpilicueta started the year off mainly on the bench for Chelsea but has been given more starts of late; he may still be a top contender to join the list on defense. Albiol has played well for Napoli but few will forget his woeful play in a friendly against Chile near the end of the year. Monreal has also been a part of Arsenal's resurgence in the Premier League.

So who could compete for spots? Del Bosque called up Inigo Martinez and Juanfran for the final set of qualifiers; he also called them up for Spain's recent friendlies with Equatorial Guinea and South Africa. Juanfran has excelled this year for Atletico Madrid and could get a very close look from del Bosque to help anchor his defense. Alberto Moreno was also called up and could be given a look in one of the World Cup qualifiers. His speed on the flanks matches that of Alba and could give Spain more of an attacking presence there. However, at age 21, his lack of experience on the big stage may make him a liability. Furthermore, Alba's tendency to venture forward has cost Spain on the counterattack; del Bosque may be wary of leaving himself exposed on both flanks.

Midfield

Del Bosque has generally used around 10 midfielders in his previous tournaments, signaling the likelihood that he may not have much room for new additions. However, Pedro, generally seen as a forward player, is often used on the wings; same goes for Jesus Navas. Fabregas presents an interesting dilemma for the manager. He was utilized exclusively as a false nine in the 2012 Euro and could function well there. However, Fabregas is more natural in the middle position currently occupied by Xavi. Could he potentially be used in both roles throughout the tournament? If this were the case than he would wind up being the forward for del Bosque, thus opening up another potential midfield position.

So who are the realistic candidates to join this assortment of midfielders? Borja Valero is enjoying a resurgence with Fiorentina in 2013-14; he has five goals and seven assists in 22 matches and could be a terrific addition for Spain as a starter or substitute. He could have a huge impact in a game against a weaker opponent like Australia in the group stage or could provide some stability against a stronger opponent.

Atletico's Koke and Raul Garcia are often thrown around as potential choices considering their team's terrific year. Koke has gotten few looks and he could very well be a lock. Garcia is likely a long-shot despite deserving a chance.

Juan Mata is another potential option for del Bosque but he has had a dismal season and would need a terrific finish with Manchester United to make his case. His play in the Confederations Cup last summer did not make a strong case for him and it is likely that the 26-year-old will not be on the roster.

Santi Cazorla is also looking to get back on the roster but he may also find it difficult considering his injury troubles and his poor play in Spain's system during last year's tournament. He might be the favorite of all the midfielders listed, however, as del Bosque has turned to him time and time again.

Aside from those three, Spain's midfield looks pretty set.

The big puzzle is at...

Forward

As noted, Pedro and Navas will likely join as wingers while Fabregas and Silva could play in a false nine position. However, Spain is in desperate need of a real forward with scoring prowess to wreak havoc on the likes of Chile and the Netherlands in the group stage.

Fernando Torres, David Villas, Alvaro Negredo and Roberto Soldado have been the favored strikers for del Bosque in recent tournaments. Torres is starting to pick up his play after a horrid start to the season for Chelsea, but four goals in 18 matches is not going to cut it. Negredo has been solid for Manchester City this season with nine goals in 21 Premier League matches; he has cooled off as of late and will need to turn it around in a hurry to earn his spot. Soldado has been a bust for Tottenham Hotspur with only five goals in 20 games; most of them have come off of penalties. He is likely not going to play at the World Cup. Villa has struggled with injuries of late but his 11 goals in 23 matches make him one of the top contenders to join the squad.

However, he will compete with fellow teammate Diego Costa who has a whopping 26 goals in 32 matches for Atletico this season. After all the effort that del Bosque made to get him to join Spain instead of Brazil, it is likely that he will be the first choice up top for Spain. His statistics this year certainly do not hurt his chances.

The other major contender is Jese Rodriguez of Real Madrid. Del Bosque recently hinted that he was interested in the youngster and it is hard to deny that the 20-year-old deserves a shot. He has five goals and four assists in 15 Spanish League matches for Madrid this year; he has only started three of those games. His playing style has been compared to that of Cristiano Ronaldo and his speed, height, scoring prowess and strength would add another dimension to the defending champs.

Fernando Llorente could also get a look. He has 10 goals in 21 matches for Juventus this year and possesses the height and strength to rattle defense. He has gotten a lot of looks of late for Spain in international friendlies.

Prediction:

The roster will likely look like this:

Goalies: Iker Casillas, Pepe Reina, Victor Valdes

Defense: Alvaro Arbeloa, Gerard Pique, Jordi Alba, Sergio Ramos, Cesar Azpilicueta, Juanfran, Raul Albiol

Midfield: Xavi, Xabi Alonso, Sergio Busquets, Andres Iniesta, David Silva, Jesus Navas, Javi Martinez, Cesc Fabregas, Santi Cazorla

Forwards: Diego Costa, David Villa, Pedro, Jese Rodriguez