Toure feels Barcelona are starting to feel the strain of playing fast-paced football with trying to clinch a third European Cup, win the Spanish league and the Spanish Cup (Copa del Rey).

BBC: Toure fears Barcelona tiredness

Since making his Barcelona debut in 2003, he has collected three European Champions League crowns, two FIFA Club World Cup titles, five Spanish league championships and two Copa del Rey medals.

CNN: Messi signs new Barcelona deal

Since making his Barcelona debut in 2003, he has collected three UEFA Champions League crowns, two FIFA Club World Cup titles, five Spanish league championships and two Copa del Rey medals.

CNN: Messi joins Xavi and Puyol in agreeing new Barcelona deals

Barcelona carried off the Spanish title, Champions League and Copa del Rey last season but Ronaldo played down any suggestion that Real could immediately replicate their bitter rivals' achievement.

BBC: Ronaldo welcomed by 80,000 fans

With Madrid, he won one Copa del Rey and one Spanish league title.

WSJ: Mourinho Appointed Chelsea Manager

The 22-year-old Messi helped the Catalan giants to the Spanish La Liga and European Champions League titles as well as the Copa Del Rey, while his Argentina side scraped into the World Cup finals after finishing fourth in their South American qualifying campaign.

CNN: Messi makes history as Europe's best

Spain international Casillas has not played for Real since being injured in January, but in his absence the reigning Spanish champions have been on a fine run, beating Barcelona in the semifinals of the Copa del Rey and in their 'El Clasico league clash Saturday, winning 2-1.

CNN: STORY HIGHLIGHTS

Their loss to Real Madrid in the Copa del Rey might even lead some pundits to put them behind Real Madrid as the second most likely Spanish side to win the tournament.

FORBES: Champions League: Why Barcelona Are Favored, Who Is the Dark Horse, & Where Are the English Clubs?