Barcelona captain Andres Iniesta says the threat posed by Club World Cup final opponents River Plate has his side worried.
Barca and River go head to head at Yokohama's International Stadium on Sunday, having seen off Guangzhou Evergrande Taobao and Sanfrecce Hiroshima respectively in the last four.
Champions League winners Barca are heavy favourites to win the global title for a record third time, but Iniesta has urged caution.
"I don't like to talk about favourites in a final. It's 50-50," he told a pre-match media conference.
"River worry ... they are a strong team and they have quality players in midfield and in attack."
Barca star Lionel Messi missed the 3-0 win against Guangzhou as a result of renal colic, but Iniesta is hopeful the Argentinian could feature in the final.
"It seems he is better," he added. "Everyone wants him to play."
