Pope Francis has appeared before about 150,000 pilgrims massed in St Peter's Square for his first Angelus prayer and asked the faithful to pray for him.
"Thank you for your welcome, and for your prayers," the first pope from Latin America said on Sunday from a window of the papal apartment high above the square. "Pray for me," he added.
Dozens of flags from Francis' native Argentina were waving in the square, along with the Vatican's yellow and white standard, as the former cardinal Jorge Mario Bergoglio recited the traditional Sunday Angelus prayer, the first of his papacy.
"He seems closer to the people. We didn't feel that with the pope we had before."
- Gabriel Solis, Argentine pilgrim
Flags from other Latin American nations including Colombia, Peru, Paraguay and Mexico, could also be seen in the crowd.
One banner read: "Francis, you are the springtime of the church", reflecting hope that the choice of a humble outsider has inspired in many Catholics weary of Vatican scandal and dysfunction.
Gabriel Solis, 33, and Argentine pilgrim, spoke of his "indescribable emotion".
"He will bring much peace because he seems more humble, more spontaneous," he said. "He seems closer to the people. We didn't feel that with the pope we had before."
Earlier on Sunday, the pope grabbed an opportunity to shake hands with well-wishers, plunging into crowds pushing against barricades outside a Vatican gate as security men and Swiss Guards stood nervously by.
Chanting "Viva il papa" and calling his name, the well-wishers jostled to meet the new pontiff, who has projected a common touch by breaking with many formal traditions since his surprise election to lead the world's 1.2bn Catholics on Wednesday.
Pope of the poor
The 76-year-old pope's informal style is markedly different from that of his more austere 85-year-old predecessor Benedict XVI, who stunned the world last month by announcing his resignation citing his advanced age.
A million people may attend the pope's inaugurating mass on Tuesday, including world leaders who are set to being flying into Rome on Sunday.
Among them is Argentine President Cristina Kirchner who had tense relations with Bergoglio, the former archbishop of Buenos Aires, before his elevation to pope.
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US Vice President Joe Biden was also due to arrive later on Sunday.
Francis, whose father was a railway worker, has already spoken to Catholic leaders about the need for spiritual renewal and evangelisation and cautioned them against worldly glories, as well as calling for a "poor church" that should be closer to ordinary people.
He warned cardinals that the church would fall apart "like a sand castle" if it did not have a solid spiritual foundation and urged them to share their wisdom - "good wine that gets better over the years" - with young people.
At the same time, Francis has faced accusations at home that he failed at the time to speak out against brutalities committed during the years of military junta in Argentina (1976-1983) when he was head of the country's Jesuits.
The Vatican has firmly rejected claims that Bergoglio failed to intervene when two Jesuit priests were tortured by the dictatorship, saying the allegations were part of a leftist, anti-clerical campaign.