Lionel Messi has denied having knowledge of the tax issues that led to fraud charges against him.
The Barcelona footballer told a court he signed documents without reading them because he trusted his father and the advisers responsible for managing his finances.
"I didn't know anything," Messi said while giving evidence in his tax fraud trial. "I only worried about playing football."
Wearing a dark suit and tie, Messi sat alongside his father in front of the judge and listened to other evidence for nearly four hours before being called in the third day of the trial.
The Argentine player looked impatient in court at times, looking down and trying to stretch his legs.
Speaking for less than 15 minutes, he said he never suspected of any wrongdoing when his father would ask him to sign contracts or documents.
"I signed what he told me to sign because I trusted my father," Messi said. "I trusted my father, and the lawyers said that I could (sign the documents)."
He said he did not know that part of his income was going through companies created in countries such as Uruguay, Switzerland and Belize, which authorities alleged was done to lower the player's tax burden in Spain.
"The only thing I knew is that we signed deals with different sponsors and they paid for me to do advertisements, photos and things like that," Messi said. "But I didn't know how this money arrived or where it was going."
Messi's father, Jorge Horacio Messi, had reiterated in his evidence that his son did not know the details of his contracts or the structures created in other countries to handle his income from image rights.
"I didn't think it was necessary to inform him of everything," Messi's father said.
Messi and his father are facing three counts of tax fraud and could be sentenced to nearly two years in prison if found guilty of defrauding Spain's tax authority of 4.1 million euro (£3.1 million) from 2007-09.
They are not likely to face any jail time but could be fined and made to forfeit possible future tax benefits. Both deny wrongdoing, and the money owed was already paid back.
The trial is expected to end on Friday and the verdict and sentencing are expected next week.
Hundreds of journalists and a few onlookers were in front of the Barcelona court house when Messi and his father arrived. Authorities had prepared a special operation to control the crowd and protect the player. Some people showed their support for Messi, while shouts asking him to "give the money back" and telling him to "go play in Panama" could also be heard.
Messi was also being investigated by Spanish tax authorities after his name was among those released in the probe of international offshore accounts, known as the Panama Papers, although he was not charged for those allegations.
When the player left the court house, many fans applauded.
Because of the trial, the Barcelona player has missed part of Argentina's preparations for the Copa America, which starts on Friday in the United States.
The trial is centred on alleged unlawful activities of Messi's father, but authorities said the player knew enough to also be named in the case. Officials said that although Messi was mostly unfamiliar with tax issues, there was sufficient evidence to believe he could have known and consented to the creation of a fictitious corporate structure to avoid paying some of his taxes in Spain.
On Wednesday, Messi's lawyers tried to show the court that the Barcelona forward was not familiar with the tax issues. Witnesses called to give evidence said Messi had little knowledge of the alleged corporate structures.
Tax inspectors told the court they found evidence that the structures were used by Messi's father to avoid paying the taxes that the player supposedly owed in Spain. A witness on Wednesday said Messi's father knew they would avoid taxes by using companies in other countries, but contended that it was a legal practice.
Messi is the latest high-profile player to have to deal with Spain's tough tax system. Neymar, Javier Mascherano, Adriano and Xabi Alonso also were targeted by authorities recently.
Mascherano, Messi's teammate with Argentina and Barcelona, was handed a suspended one-year prison sentence earlier this year for not paying nearly 1.5 million euro (£1.1 million) in taxes for 2011-12.