Argentina defender Roberto Ayala said a knee problem which forced him to pull out of a training session on Saturday was just a scare and that he was fit for the Copa America.

"Fortunately, I'm fine. I woke up this morning with no pain and was able to train in the gym with my team mates," he told reporters on Sunday.

Ayala, who has made a record 109 appearances, said he withdrew from the previous day's practice as a precaution.

Argentina have arrived in Venezuela as slight favourites to win the Copa after Brazil's top pair Kaka and Ronaldinho asked not to be picked, saying they needed a rest.

"We are favourites because Argentina always are," said Ayala. "But we have to prove it on the field.

"The only idea we have in our heads is to win because Argentina haven't won anything for a long time."

Argentina, who lost to Brazil in the 2004 final, face the United States, Paraguay and Colombia in Group C. They open against the U.S. on Thursday.

Argentina last won the Copa America in 1993.