Tens of thousands of pilgrims packed Rio de Janeiro's streets to greet Pope Francis on Monday, joyfully swarming his car and chanting his name in a country recently rocked by social unrest.
The 76-year-old Argentine, making his first trip abroad since becoming the first Latin American pontiff, was surrounded by throngs of cheering faithful as he was driven through the Brazilian city.
But the first day of his visit was marred by violence when riot police used tear gas and water cannons to disperse hundreds of people protesting the cost of his visit after he met President Dilma Rousseff at the state governor's palace.
A news photographer was seen on the ground with his head bleeding.
Moments earlier at the nearby palace, the pope had urged young Roman Catholics to "go and make disciples of all nations."
Rousseff's popularity has plunged in recent weeks, amid frustrations with corruption and the pace of economic growth. The leftist and Brazil's first female president acknowledged the social discontent, saying Brazil's youth was fighting for "a new society."
After massive protests over lagging public services and corruption regularly spiraled into violence in recent weeks, authorities wanted to ensure an incident-free visit for the pontiff.
Despite the heavy security, with 30,000 soldiers and police mobilized, several people were able to stop the pope's car convoy and touch him through his open window. The pope shook hands and kissed babies.
The army meanwhile said soldiers discovered an explosive device during a training session on Sunday in a bathroom at the Shrine of Our Lady of Aparecida in Sao Paulo state, which the pope will visit on Wednesday.
The homemade device was destroyed and authorities said it was nowhere near the area where the pope or pilgrims will congregate.
Pope Francis came to Brazil, an emerging power with a shrinking Catholic flock, to promote his vision of a more humble church and to attend World Youth Day, a week-long event drawing more than one million young Roman Catholics.
Excitement about his first overseas visit brought huge crowds into the streets, chanting "long live the pope," singing and waving the flags of Argentina and other countries.
The pope, first in a small four-door car and then an open-top jeep, waved at the faithful after deciding to leave his armored "Popemobile" behind, a decision that unnerved local authorities.
"I have learned that, to gain access to the Brazilian people, it is necessary to pass through its great heart; so let me knock gently at this door," Francis said at the governor's palace.
"I ask permission to come in and spend this week with you. I have neither silver nor gold, but I bring with me the most precious thing given to me: Jesus Christ," said the pope, who will lead an open-air sermon on Copacabana beach on Thursday.
Vatican spokesman Federico Lombardi said the pope was not worried about the massive crowd and that he wanted to avoid a "militarization"of security, but he went to the governor's palace by helicopter to avoid the protest.
"The pope's secretary told me he was terrified, but the pope kept smiling" at the throngs swarming his car, Lombardi told reporters, adding that there was "no particular concern" about the explosive found at Aparecida.
The Church in Brazil, the world's biggest Catholic country, has seen its following dwindle in the face of growing Evangelical congregations and spreading secularism.
More than 90 percent of Brazilians identified as Catholic in 1970, according to the census.
But a poll by Datafolha Institute on Sunday showed just 57 percent now call themselves Catholic, while 28 percent say they are Pentecostal or non-Pentecostal Evangelicals.
"We hope the pope will bring us the renewal of faith and enthusiasm," said Renzo Cicroni, a 23-year-old Argentine who joined the crowds cheering the pontiff.
"To see all these young people together, it re-energizes us."
Anaia Betarte, a 17-year-old from Uruguay, said she came to "see change, something new, something refreshing."
The pope's message of a "poor Church for the poor," may play well in Brazil, which is now an economic powerhouse but still has millions living in shantytowns like the favelas rising on Rio's hillsides.
Speaking on the papal plane, Pope Francis warned against marginalizing the young and the elderly.
"The global crisis has brought nothing good to young people. I saw the data on youth unemployed last week. We run the risk of having a generation without work," said Francis, who carried his own luggage onto the plane, in keeping with his trademark simplicity.