Former Barcelona fullback Juliano Belletti believes that Brazilian side Santos can upset the Club World Cup favourites in Yokohama this weekend.

Belletti, who is well remembered for his Champions League winning goal against Arsenal in 2006, insists that his former club cannot go on winning forever as teams will work out how to beat them.

"Teams already know how to score [against Barcelona]," Belletti told Lancenet. "Players get older, life goes on.

"For the other teams as well as Barcelona, it will become difficult to keep up the pace.

"Santos can win. There will be no favourites during the 90 minutes, anything can happen."

Meanwhile, Barcelona boss Pep Guardiola has likened Santos to rivals Real Madrid.