The charismatic pontiff will fly into the capital of Manila late today afternoon from Sri Lanka, where a million worshippers gathered to watch him canonise that nation's first saint and listen to a homily on religious tolerance.
Francis has said his two-nation tour is aimed at adding momentum to already impressive growth for the Church in Asia, with its support in the Philippines the benchmark for the rest of the region.
The high-point is expected to be an open-air mass at dusk on Sunday at a park in Manila, with organisers preparing for up to six million people despite a forecast of rain and security concerns.
"I really want to see the pope, not just see him on a TV, so I am prepared to sacrifice," said saleswoman Vanessa Tupaz, 54, referring also to worries about the dangers of being in such a huge crowd.
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Organisers have said that, if the crowd is as big as expected, it will surpass the previous record for a papal gathering of five million during a mass by John Paul II at the same venue in 1995.
Francis, who will be making the fourth papal visit to the Philippines, is also due to visit communities devastated by Super Typhoon Haiyan, which killed or left missing 7,350 people in 2013.
Church officials have said one of the main reasons for Francis wanting to visit the Philippines was to make a "mercy and compassion" trip to meet survivors of the typhoon.
Authorities have expressed major concerns over the pope's security in the Philippines, where attempts have been made to kill visiting popes twice before.
Nearly 40,000 soldiers and police are being deployed to protect the pontiff in what Philippine military chief General Gregorio Catapang described as a "security nightmare".