A Saturday evening vigil in Rome was to officially launch celebrations for Sunday's beatification of John Paul II, which will mark the penultimate step in the process to make the late pontiff a saint, DPA reported.
The French nun whose healing was recognized by the Vatican as the miracle needed for John Paul's beatification planned to share her story with piligrims at the vigil.
Sister Marie-Simon-Pierre had been diagnosed with Parkinson's disease but was cured in June 2005, allegedly thanks to the intercession of John Paul, who died on April 2 of that year. He had also been afflicted by Parkinson's.
Pope Benedict XVI was also scheduled to address the vigil ceremony, to be held at the Circus Maximum - once an ancient Roman chariot-racing arena - through a video message.
After the vigil, eight central Rome churches were set to remain open all night for pilgrims to pray.
On Sunday, Benedict was scheduled to celebrate the beatification mass in St Peter's Square.
Dozens of international leaders were expected to attend, including from John Paul's native Poland President Bronislaw Komorowski, Belgium's King Albert II and Queen Paola, Mexican President Felipe Calderon and French Prime Minister Francois Fillon.
On Friday the Vatican said Zimbabwe's controversial President Robert Mugabe would also be expected to attend the beatification mass.
Mugabe is subject of a travel ban by the European Union, which accuses him of human rights violations. The Vatican however, is a sovereign state and is not a EU member.